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shane alward
New User
Username: the_gambler

Post Number: 2
Registered: 5-2015
Posted on Tuesday, 16 June, 2015 - 20:49:   Edit PostDelete PostView Post/Check IP

hi can anyone please give me advice on the correct fuel to use in a silver shadow SRH8556. do I need to use lead replacement....thanks shane
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Brian Vogel
Grand Master
Username: guyslp

Post Number: 1398
Registered: 6-2009
Posted on Tuesday, 16 June, 2015 - 22:57:   Edit PostDelete PostView Post/Check IP

You can safely use regular unleaded in these cars. There is no need to use "lead replacement" because the cars were designed to be able to use fuel in many markets where unleaded was all that was available.

You need not go to mid-grade or premium fuel unless you have knocking/pinging with regular grade unleaded fuel. I have yet to know a Shadow owner that's had any trouble with regular grade unleaded.

Brian
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Mark Aldridge
Prolific User
Username: mark_aldridge

Post Number: 217
Registered: 10-2008
Posted on Tuesday, 16 June, 2015 - 23:38:   Edit PostDelete PostView Post/Check IP

Some years ago , I think Richard Treacey posted the Crewe timing settings for alternative octane fuels for Crewe cars. I found power loss by adjusting ignition timing for 95 Ron, and use supergreen (97 Ron) plus Tetraboost to give the original recommended fuel grade. I have also noticed cooler running particularly on high compression ratio engines using tetraboost. This is in the UK.
Mark
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Brian Vogel
Grand Master
Username: guyslp

Post Number: 1399
Registered: 6-2009
Posted on Wednesday, 17 June, 2015 - 00:46:   Edit PostDelete PostView Post/Check IP

Mark,

Thanks for jogging my memory with regard to the engine timing document. I forget that this is out there. See the document entitled, Postwar Vehicles - 1946 to 1999: Engine Settings in the technical library.

Brian
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Geoff Wootton
Grand Master
Username: dounraey

Post Number: 769
Registered: 5-2012
Posted on Wednesday, 17 June, 2015 - 01:33:   Edit PostDelete PostView Post/Check IP

Wow, what a difference. Here's the extract for SY1's from SRH8742 to SRD22117.

data

99RON = 5'btdc
97RON = 5'atdc (AFTER!!)

I'm currently running on premium which, according to the wiki page can be anything from 95 - 99 RON. All a bit vague. Regular is given as 90-91RON, which means you would, in theory, have to set timing at around 10'atdc.

I know Paul, in a recent posting said to advance by 5' due to the slower burn of modern petrol with 10% ethanol.

Confused - lol.

My car is currently time at 8' BTDC and is not pinking. It should be jumping out of the engine bay according to these figures.

If Mark had to adjust his timing to ATDC, then no wonder he lost power.

Geoff
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Geoff Wootton
Grand Master
Username: dounraey

Post Number: 770
Registered: 5-2012
Posted on Wednesday, 17 June, 2015 - 01:57:   Edit PostDelete PostView Post/Check IP

Thinking about it, as I'm running on premium, which is high end RON, then adding on the 5' for ethanol petrol I am running at around 3' BTDC, since these charts were produced on the older, non ethanol petrols. Which is probably about right.

I was thinking of checking out regular at some time in the future, but it looks like the engine has to be retarded far more than I would have expected.

Geoff
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Brian Vogel
Grand Master
Username: guyslp

Post Number: 1400
Registered: 6-2009
Posted on Wednesday, 17 June, 2015 - 02:02:   Edit PostDelete PostView Post/Check IP

Geoff,

Please forgive me if this seems to be insulting, as it's not meant to be, but remember that octane ratings shown on pumps in the USA are AKI, which is (RON + MON)/2. You add approximately 10 points, roughly, to AKI to come up with RON values. Our regular unleaded, which is typically 87 AKI octane is about 97 RON octane.

Premium fuel, which is typically between 91 and 93 AKI, is approximately 101 to 103 RON.

Also, is there a direct reference to these values being on fuel that does not contain ethanol? I hadn't noticed that, and given that this appears to have been pulled from IETIS, which was issued at its earliest for 1990 model year cars, E10 fuel was ubiquitous (and not only in the United States) by that time. I'd be surprised if E10 wasn't what was used.

Brian
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Geoff Wootton
Grand Master
Username: dounraey

Post Number: 771
Registered: 5-2012
Posted on Wednesday, 17 June, 2015 - 02:44:   Edit PostDelete PostView Post/Check IP

Brian

Insulted!!! I'm enraged. I've loaded my baseball bat and I'm on my way over to your place.

Actually, that changes everything. It should be quite ok to use regular gasoline without any appreciable loss of power. I know we have broached this subject before and I was just waiting for a good time to convert to regular. There is absolutely no point paying the extra 25c per gallon if the engine runs as well on it. It may be that regular UK petrol is of a lower octane rating to here in the US, which would explain Mark's loss of performance.

Geoff
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Brian Vogel
Grand Master
Username: guyslp

Post Number: 1401
Registered: 6-2009
Posted on Wednesday, 17 June, 2015 - 03:12:   Edit PostDelete PostView Post/Check IP

Geoff,

I'm already cowering!!

I also confirmed that this document is indeed composed of data released in IETIS for the 1990-2000 model year cars and is quoted verbatim.

I've always followed the advice of Consumer Reports, which is no slouch in testing and long term observation of field results, with regard to gasoline/petrol. They've said for decades that you can and should use the lowest octane fuel that you can use that does not cause your car's engine to knock/ping/pink and that does not result in performance characteristics you find unsatisfactory. I hasten to add that they don't suggest you "downgrade" in truly modern vehicles engineered for specific octane rating ranges. However, the SY cars don't fit that paradigm and were engineered so that they could run on the fuel available anywhere they happened to land, with slight tweaking to customize to that fuel.

With modern computer-controlled ignitions you can (and I did, after accidentally filling the tank of my Jag with regular instead of premium) run virtually any car on regular and it will compensate for that on its own. If maximum performance is essential to you in a performance vehicle then that won't work, but if you're using it for typical commuting or road trips it certainly might.

For older cars, virtually any of them can be adjusted to run on the fuel available in their "place of residence," and that's what you need to do anyway. I never expect to see anything but E10 available anywhere in the USA as the typical fuel, so I want my cars to be prepared to use what's available, and at the lowest octane rating at which they can "be happy." Why burn money, literally. I certainly have no intention of pushing any car, let alone a Rolls-Royce, to anywhere near to its limits. The idea of pushing a Silver Shadow/Wraith to anywhere near to its limits is actually kind of frightening.

Brian
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Geoff Wootton
Grand Master
Username: dounraey

Post Number: 772
Registered: 5-2012
Posted on Wednesday, 17 June, 2015 - 03:32:   Edit PostDelete PostView Post/Check IP

Hi Brian

Thinking about it, given that US regular is 97RON, then the extract above for SY1 cars states the ignition should be timed at 5'ATDC. 5'BTDC for premium is a massive difference to 5'ATDC for regular on the SY1s'. It appears the SY1 may be prone to significant performance loss, even for normal driving, if 97RON is used on these cars.

If you check out the SY2 cars, the timing differences for the most part are only from 25'BTDC to 20'BTDC.

Geoff
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Brian Vogel
Grand Master
Username: guyslp

Post Number: 1402
Registered: 6-2009
Posted on Wednesday, 17 June, 2015 - 03:43:   Edit PostDelete PostView Post/Check IP

Geoff,

Although I am unable, in any way, to confirm my suspicion it seems to me that there may be a typographical error at play here. It wouldn't be the first time, that's for sure.

The differences in fuel 2 RON points apart, or even 5 RON points apart, wouldn't seem to fit what people have been doing in actual practice with these cars. There are probably enough participants in these forums who have done timing tweaks for SY1 cars related to fuel that we could determine whether practice and "theory" (which is what I'm calling the chart for my purposes) diverge.

Something just seems off here. I certainly wouldn't go to an ATDC timing if no functional issues were occurring with a BTDC timing. What is working IRL (In Real Life) is what's important whether it matches the recommendations or not.

Brian
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Mark Aldridge
Prolific User
Username: mark_aldridge

Post Number: 218
Registered: 10-2008
Posted on Wednesday, 17 June, 2015 - 04:37:   Edit PostDelete PostView Post/Check IP

In the UK Regular fuel is 95 Ron; Supergreen is 97 Ron up to 99 Ron ( Shell & Tesco supermarket ) Max ethanol is 5%. On a 75 Shadow the recommendation is 2-4 degrees retard on the timing to use 95 Ron.
Mark
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Robert Noel Reddington
Prolific User
Username: bob_uk

Post Number: 130
Registered: 5-2015
Posted on Wednesday, 17 June, 2015 - 04:40:   Edit PostDelete PostView Post/Check IP

All Shadow engines have hardened valve seat inserts.

Often because valve seats cannot be cut into aluminium cylinder heads. A valve seat insert is used. So the makers might as well fit hardened seats.

However some aluminium heads may have soft seats. So always check first before running Sans Plumb.

Running unleaded and soft valve seats is ok for say 20 miles but once thd lead on the seats has worn away then its valve seat recession time.

Ignition timing for lower octane fuels is best set at the recommended setting and then fine tuned using the does it knock or pink method. I have found the recommended settings are about right.
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Geoff Wootton
Grand Master
Username: dounraey

Post Number: 773
Registered: 5-2012
Posted on Wednesday, 17 June, 2015 - 06:15:   Edit PostDelete PostView Post/Check IP

I guess the key to all this is the compression was lowered in Autumn 1975 from 9:1 to 8:1 and 7.3:1 on US/Australian cars (source = Marinus Rijkers website). This would account for post 1975 cars having their recommended timing specified at 25'BTDC and pre-1975 at just 5'BTDC. It would also account for why Mark's car suffered quite a loss in performance when tuned for regular petrol whilst Brian's cars did not.

Geoff
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Mark Aldridge
Prolific User
Username: mark_aldridge

Post Number: 219
Registered: 10-2008
Posted on Wednesday, 17 June, 2015 - 08:29:   Edit PostDelete PostView Post/Check IP

I had to strip the heads off my 1983 Spirit due to a very badly burned exhaust valve. This car had been set to run on 95 Ron, by a previous owner in the "wedding business". Neither the valve seats or the valves looked in their first youth , to be polite; mileage was approx. 120k miles from memory. I replaced the wrecked valve, reground the rest and reassembled but realistically it needed all new exhaust valves and probably seats for a quality job. It was still running well 2 years and 25,000 miles later . As a result of this, I would never use 95 Ron fuel and I use either a lead substitute or Tetraboost Lead additive in the fuel for all of my cars. Overhauling the V8 heads is a lot of work !
Mark
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Robert Noel Reddington
Prolific User
Username: bob_uk

Post Number: 132
Registered: 5-2015
Posted on Wednesday, 17 June, 2015 - 10:43:   Edit PostDelete PostView Post/Check IP

Mark.
Its only 2 times the work of a 4 cylinder engine.

Using the old valves is ok and 25,000 miles proves a point about fitting lots of new parts simply because while they are out we might as well fit new for the sake of it.

Most likely the valves and the engine happily run for years and many miles. This sort of thing is an engineering judgement call.
You got the call bang on the money or the money saved.

Exactly why the valve failed will always probably be a mystery. I can't imagine why weddings would cause a problem. Usually burnt valves is retarded ignition but why only one valve. I suspect a hydraulic lifter got pumped up and jammed then sorted itself out.
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Mark Aldridge
Prolific User
Username: mark_aldridge

Post Number: 220
Registered: 10-2008
Posted on Wednesday, 17 June, 2015 - 18:33:   Edit PostDelete PostView Post/Check IP

Bob, all of the valves showed signs of burning, and the heads were extremely difficult to remove due to seizure on to the studs. Also there were signs of past use of red antifreeze causing staining in the headgasket. Timing was well retarded.Car now sold after 3 years and 35k miles, daily use. Lesson learned, check on any car purchased timing is at original manufacturers setting.
Mark
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shane alward
New User
Username: the_gambler

Post Number: 3
Registered: 5-2015
Posted on Thursday, 18 June, 2015 - 19:36:   Edit PostDelete PostView Post/Check IP

great response thanks. still not sure to make the plunge to straight unleaded. what are you guys
here in aus using. to bad you have so much E10 in u.s.a. I don't know anyone that uses E10 in Australia I personally wouldn't put it in my mower let alone my rolls Royce. heard it does bad things to marine engines so I use premium in my boat also. shane
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David Gore
Moderator
Username: david_gore

Post Number: 1651
Registered: 4-2003
Posted on Thursday, 18 June, 2015 - 20:06:   Edit PostDelete PostView Post/Check IP

Shane, E10 is an absolute no-no for marine applications due to problems with water condensation in fuel tanks reacting with the ethanol. I have heard of numerous sea rescues being undertaken by our local marine rescue volunteers due to engine failures caused by use of E10 fuel by "weekend boaters" filling their trailer boats at service stations whilst unaware they should have been using straight unleaded fuel. You will not see E10 fuel at any marina fuel point but their higher price encourages casual boaters to go for the cheaper service station fuel.
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Geoff Wootton
Grand Master
Username: dounraey

Post Number: 775
Registered: 5-2012
Posted on Friday, 19 June, 2015 - 00:12:   Edit PostDelete PostView Post/Check IP

Both Shane and David use the term "straight unleaded" in describing petrol/gasoline in Australia. It implies that leaded fuel is still used in Australia. Is this just a term used for lower octane rated fuel or are you still using lead tetra-ethyl as an additive.

Geoff
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Geoff Wootton
Grand Master
Username: dounraey

Post Number: 776
Registered: 5-2012
Posted on Friday, 19 June, 2015 - 00:56:   Edit PostDelete PostView Post/Check IP

My advice on running on lower octane rated fuels is be very careful if your car is the earlier model (pre 1975) with the higher compression engine. The problem is these cars have a factory timing setting of just 3-5 degrees BTDC. Using a lower octane fuel will likely require the ignition timing to be retarded to well after TDC. The problem with this, is the fuel needs to be fully burned on the power stroke of the piston so that the much cooler, fully combusted exhaust gases are pushed out through the exhaust valves on the exhaust stroke. If the ignition is too retarded then you will be blowing superheated and still burning gases right past your exhaust valves and into the exhaust manifold. On another forum, an owner reported just such an occurrence and his exhaust manifold was visibly glowing red hot. His solution was to advance the timing and the problem was resolved. Living proof of what happens if your ignition timing is too retarded.

By setting the ignition timing to after TDC you are effectively reducing the compression ratio, since the piston is now moving away from the cylinder head. In doing so you are exposing more of the cylinder walls to the burn and in doing so burning off the lubricating oil. The more retarded after TDC, the more you expose those cylinder walls. Also, by reducing the compression ratio in this way, you are slowing the burn on an already slower burning fuel. If you are using E10 then you are slowing the burn even further - plenty of scope here for wearing out those expensive to replace cylinder liners and also applying a powerful blowtorch to your opening exhaust valves.

So, I would be very careful in moving to a lower octane rated fuel on these pre 75 cars. At the very least I would use a timing gun to know exactly how much the engine has been retarded and try and get information on how detrimental this new setting might be.

The post 75 cars are of course different. They have lower compression ratios and a factory ignition timing of 25 degrees before TDC. The documentation specifies 20 degrees for lower octane fuels, so it is arguable, given the slower burn of modern fuels, that no adjustment to timing is required at all.

Geoff
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Brian Vogel
Grand Master
Username: guyslp

Post Number: 1405
Registered: 6-2009
Posted on Friday, 19 June, 2015 - 01:08:   Edit PostDelete PostView Post/Check IP

Geoff, I read "straight unleaded" as I would "pure unleaded," that is, not blended with The Demon Ethanol®.

Those I know who are involved with marine applications have said that ethanol is mainly a problem for them due to the fuel tank sealants that were used for decades in the manufacture of fiberglass tanks. It is apparently not ethanol resistant. It's interesting to see that marine applications in the US that are currently being produced are also being set up to accept E10. With the demise of MTBE to oxygenate gasoline/petrol, ethanol has stepped in to take its place.

All of the above applies exclusively to the USA, my country of residence. I cannot speak to what other nations are doing.

Brian
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Geoff Wootton
Grand Master
Username: dounraey

Post Number: 777
Registered: 5-2012
Posted on Friday, 19 June, 2015 - 01:29:   Edit PostDelete PostView Post/Check IP

Hi Brian

I am sure you are right. It is hard to imagine any country is still using leaded fuel.

I remember the opposition to removing tetra-ethyl lead, from the motoring press in the UK in the seventies. The fear was the performance of our cars would be reduced by doing so. Poisoning our children with atmospheric lead compounds was considered a small price to pay in ensuring we got maximum performance. Funny, I didn't agree with them.

Geoff
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Brian Vogel
Grand Master
Username: guyslp

Post Number: 1406
Registered: 6-2009
Posted on Friday, 19 June, 2015 - 02:06:   Edit PostDelete PostView Post/Check IP

Geoff,

Yes, the automotive press in the USA was no better, nor was the hobbyist community. The removal of lead from fuel was going to be the demise of virtually every engine already on the road, and in short order. Funny, but that never happened and most people didn't even notice.

It amazes me that when these changes are to take place that certain elements seem to believe that no consideration to backward compatibility is given. Unleaded has anti-knock additives, just not lead. I've said before that if someone could show that sand worked just as well as lead and didn't damage engines then I can't see why anyone should have a "personal preference" for one over the other.

Clearly, it's another of those 'twas ever thus things. People hate change and tend to trust anecdotal evidence or urban legends above all else when either confirms their biases.

Brian
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David Gore
Moderator
Username: david_gore

Post Number: 1652
Registered: 4-2003
Posted on Friday, 19 June, 2015 - 10:17:   Edit PostDelete PostView Post/Check IP

"straight unleaded" = unleaded with no ethanol.

Leaded fuel [100/130 and 100LL octane] is still available in Australia exclusively for aviation use and I presume this still applies elsewhere in the world due to the requirements for light aircraft piston engines. Heavy fines apply to anyone found supplying aviation fuel outside the aviation industry however I would not be surprised if the contents of an occasional drum of avgas disappears from rural properties with an airstrip and refuelling facilities for light aircraft kept on the property.

Our fuel ratings are:

straight unleaded: 91 RON
E10 unleaded: 92 RON
unleaded 95: 95 RON
premium unleaded: 98 RON

For R-R/B V8 engines, fuel choice is determined by the compression ratio of the engine and whether it is pre-emission or post-emission control specification. DRH14434 was an imported 9:1 pre-emission UK vehicle which had fuel specified as 100 octane but would run on 95 octane with the timing retarded by 2 degrees. Australian-delivered V8 cars had the "colonial engine" with 7.3:1 or 8:1 compression ratios depending on the year of manufacture; these cars accept straight unleaded without any problem and can use E10 if they are fitted with the Burlen carburettor/fuel pump kits to adapt them for ethanol blend fuels.

As I have previously stated, I regard Australian ethanol blended unleaded as a "con-job" as it does not have the same energy content as straight unleaded and increases fuel consumption by around 10% for a price reduction of around 3%. Many service stations that only stocked E10 unleaded are now stocking straight unleaded with the E10 as they were losing sales to stations stocking straight unleaded.

Brian, the E10 marine problems have been mainly due to water contamination from condensation in the tank combining with the ethanol and separating out as an ethanol/water mixture in the bottom of the tank where it is picked up by the fuel pump - this fluid does not have good combustion characteristics!! A similar thing happens with bio-diesel, the fuel/water mixture is more prone to pick-up from the tank and will not ignite when compressed in the cylinder. To the best of my knowledge, fibreglass marine fuel tanks are not common in Australia with metal and moulded high density polyethylene being most common.
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Robert Noel Reddington
Prolific User
Username: bob_uk

Post Number: 145
Registered: 5-2015
Posted on Saturday, 20 June, 2015 - 04:44:   Edit PostDelete PostView Post/Check IP

In the UK we don't have E10. I am not entirely sure what petrol is any more.

My jeep being a 1993 UK spec. Is designed for modern "petrol"

My SRH 17768 was designed for the petrol of that time.

LPG I believe is over 100 RON.
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Mark Aldridge
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Username: mark_aldridge

Post Number: 221
Registered: 10-2008
Posted on Saturday, 20 June, 2015 - 05:22:   Edit PostDelete PostView Post/Check IP

In the UK Tetraboosst is readily available( although adds about 17p per litre to fuel cost. The claims , from my experience are correct, and I use it in all of my cars made before UK went unleaded, if they are used for prolonged hard or fast driving. http://tetraboost.com/
Mark
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Robert Noel Reddington
Prolific User
Username: bob_uk

Post Number: 147
Registered: 5-2015
Posted on Saturday, 20 June, 2015 - 06:28:   Edit PostDelete PostView Post/Check IP

Does tetra boost give more mpg if one doesnt use the extra power thus offsetting the cost maybe all of the cost.
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Mark Aldridge
Prolific User
Username: mark_aldridge

Post Number: 222
Registered: 10-2008
Posted on Saturday, 20 June, 2015 - 08:27:   Edit PostDelete PostView Post/Check IP

Bob, I have not checked this but it does slightly reduce running temperatures on all of my cars and stops pinking on my Mg Midgets ( 10:1 cr. etc) Also it has avoided me having to fit hardened valves and seats. I use it on the Crewe cars as an insurance against (hopefully) a repeat of the Spirit problem.My cars are regularly used(they are my wife,s and my only cars other than my company Landrover) and therefore driven quite hard and used for a lot of motorway work.In total they exceed 20k miles pr year.
Mark
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Robert Noel Reddington
Prolific User
Username: bob_uk

Post Number: 150
Registered: 5-2015
Posted on Saturday, 20 June, 2015 - 09:28:   Edit PostDelete PostView Post/Check IP

Mark,
Providing the RR V8 is set up correctly which no doubt yours is, then the engine will not be damaged by spirited driving within reason remembering that 80 mph is about it before one gets nicked and the engine will do 80 with ease.

6750cc and 220Bhp is a low state of tune. The engine doesn't produce enough power to hurt itself.

The turbo R is more or less a Shadow engine with a turbo "nailed" on. Note that the turbo R has many other differences and that one cannot just bolt turbos on engines. Well you can but try to get it to run right is a whole different ball game.
The extra power output hasn't seem to shortened the engines life. The main reasons for that is that at say 60 mph not much power is needed. Continously driving a turbo flat out will probably kill the driver.

Oil wise I have to recommend a fully synthetic. Synthetics start off as say 30 weight and additives are added to make it behave like a zero grade - 0/30. When the additives start to die the oil gets thicker.
Mineral oils are the opposite these start off as say 20 grade and vi improvers take it to 50. 20/50. As the vi improves get used up the oil get thinner.

However both oils if left in the engine long enough will both get thicker.

Note At say 90c a 20/50 and a say 10/40 oil will have the same viscosity. Also note that when new both mineral and synthetic oil are about equal in performance. Its as the miles build that makes them different. With mineral being the loser.

However if you like tetraboost and it works then its fine.

I dismiss 99% of engine oil additives as snake oil. But I have found some fuel treatments do work. We had a injector flush machine at the police which worked well on dribbling petrol injectors. I think the fluid was acetone based.

I filled up a motor bike cylinder with Redex and left it for a week. Then started it. I got an increase in compression and the bike went better. BSA C15 250cc single cylinder.