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4 Star in my Waggon

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[:(] My Porsche is a 911SC, 204 bhp 1981vintage.
Now Shell is doing away with 4 Star by the end of this year I am at a loss of what to do !
Some say use Shell 95 octaine.
Some say use Shell Opitmax 98 octaine.
Some say use an additive with 95 or 98 octaine.
The hand book states 98octaine for 204 bhp models only.
Are the valves hard enough to use 95 and would I need to adjust the timing; or just use 95 and see if she "pinks"?????
While we are at it is Mobil 1 the best oil for her and how long for an oil change 6k or 12k ?

Tr50175.jpg
 
Vin,

Your car will run unleaded with no trouble at all, there will be no problems with the valves! I run Shell optimax in my 83.

As for the oil, you'll get loads of different answers on this one! Personally I use Fully Synth Magnetec. There's a theory that 'thin' synthetic oils can actually cause a dry engine to leak, and for that reason alot of folks stick with dino oil. If you are using Mobil 1 at the moment and have no problems stick with it, it's an excellent oil.

Cheers,

Tim.
 
All 911 engines from 73 onwards,when unleaded was first used in the USA, have valve seats suitable for unleaded according to independent specialists.You can use 95 RON and adjust the timing or check out the AMD website for a K Star modified ignition pack that gives mapped ignition to cure the problem once and for all with no loss of power.
For oil avoid the O W /40 Mobil it will just leak out or get burnt by an old 911.Mobil also make thicker stuff for older engines.I prefer to use something reasonable like Comma 15W/40 semi synthetic and change it every year even if I only do a couple of thousand miles.If you've got your handbook in the back it gives all the oil specs and any decent quality oil exceeds the factory spec nowadays.
Forget the hype; Porsche changed from Shell to Mobil oil when a certain M Schumacher joined Ferrari and they changed from Agip oil to Shell.Porsche could never be seen to have the same oil as a Ferrari they are the enemy!!!
 
Unless you are doing tens of thousands of miles in your car I would suggest using Optimax or BP Ultimate.

AFAIK Shell stopped 4 star about 3 years ago. They may have introduced an LRP, which they are now phasing out.

Of course proper leaded 4 star is still available...... at around £1 per litre. look at http://www.leadedpetrol.co.uk/list.htm
 
I use Optimax because I have heard good reports about it's cleaning properties. Occasionaly run un-leaded or other with no noticable difference in power, but then who times their 0-60 performance with a stop-watch?
My car was just serviced when I bought it and I am not sure what oil they used but I did a 6000 mile oil change a few months ago and used GTX. Since then it has used noticably less oil to the extent that I have not had to top it up, which I alway had to before. There were no leaks before or since so I can only think it's burning less. I go with the thinner synthetic oil, older engine (94k miles) not good theory, but everyone has their own take on it.
 
I use Optimax. As for oil, I use Mobil 1 0W40 with no leaks and my engine hasn't been rebuilt. As Tim says above, if it's working for you so far, stick with it.
 
So does this mean that my 1978 911sc will run fine on 95 unleaded and optimax, because i have running it on LRP and full flavour 4 star at £1 a litre for a while now.

cheers Tim
 
Does your car have a restrictor in the fuel filler opening ? ....It's for the narrow unleaded fuel nozzle on the forecourt pump! This alone would indicate the engine was designed to run with standard ie 90 octane unleaded fuel.

Before I overhauled my '72 2.4 it was running on Mobil 1 and used about 1 litre every 2,000 miles approx & smoked when cold, since top end done....which includes rings/valve guides, done 5,000 miles and put in 0.5 litre. [8|]
 
Sorry ...forgot to add any fully synthetic oil is good for 1 year or 25,000 miles in a petrol engine, whichever comes first ....that's the manufacturers recomendation.
But as always this will have a built-in margin for error....so no one ever damages an engine......so I'm currently examining the additive package for these oils to see if they are really as time constrained as this. [8|]
 
Yes Mark 90 oct for the 70's american market.......remember we had 92 octane fuel as a standard way back then.......or is it just my old memory playing tricks again? [8|]
 
Now I remember.......2,3,4 star fuel when the star rating was first introduced, followed by 5 star for only a couple of models......come on Geoff I think you've a better memory than me for which cars this was for; I was only a humble apprentice when I started driving in '69 ....Fiat 500... 2* fuel...very cheap to run...only earned £9/week...fuel 4/6d a gallon (thats four shillings & sixpence to you youngsters, about 22.5p)

I think it was 2 * 92; 3* 95; 4* 97......which eventually was upped to 98 and I think 2* was upped to 93 before it was phased out.

Incidently.....how long ago do you think we were preparing for unleaded fuel in the industry?
I worked on this for the first time 25 years ago!!!!! (Plant testing to see what the costs were....forced us to build new plant to stop the cost being prohibitive, hence the lead time). [8|]

I'm not really an insomniac......nights this weekend!
 
The hand book states 98 octaine for 204 bhp models only.
Click to expand...

Sorry just realised it's 204 bhp SC......as your buddies above suggest 98 octane Optimax; it may pink a bit under load with the BP Ultimate but it would not do any harm in the short term if you wanted to experiment to gain some flexibility if there's not a Shell station nearby.

Bet you can't tell it's a quite night here!
 
Yes Mark 90 oct for the 70's american market
Click to expand...

Now you are complicating things...

Octane rating in the USA is not on the same scale as Europe. Their 90 is about the same as our 98 or something!

So do you mean 90 USA, or 90 UK?

(Wow this could get fun!)[:D]
 
followed by 5 star for only a couple of models
Click to expand...

It used to be used in Rover V8 and the Jag that had 2 fuel tanks (this is in the late sixties/early seventies) - 2 fuel tanks was a real b*gger - 'X in the right, Y in the left' (this in my days as a forecourt attendant - no self service !).

Whether these cars needed 5*, or just 'cause they were showing off their wealth, who knows. I wonder if it still goes on ?

Oh, and people used to get 3* by mixing 2* and 4* - I kid you not, that is what they asked for !
 
Hi Mark,
Worser & worserer indeed.........there was something in the back of my mind last night and I've just found it.....we were making fuel for the States back then as we had a surplus in GB, we were indeed making it to 90 Lead free BUT adding a 110 Oct cracked cut to it & I don't know what the finished market spec was! Could easily be 95 and I will also check scales USA vs European octane ratings.
I will 'e' mail a couple of older guys in the states to see if they remember...may take a couple of days.
Problem for me remembering is that we didn't do this for long as European market soon caught up with total petrol production & exports to USA finished. [8|]
Interesting init!
 
[:D]Wow guy's didn't mean to start a war !!!
Thanks for the responces and the very interesting history lessons.
It is obvious that the question of the right fuel is passionate to get it right and not blow the engine in the long run.
I notice no one mentions additives ! any reason for this or does this open another can of worms???
Vin.
 
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