Only reason I can think that u can't is that the valves and valves seats are only designed around super or normal unleaded? Then again maybe the knock sensor could adjust the timing/ignition?
I think 4 star (Which u can still buy as the government has allowed it for some cars that need to run for going to shows etc) was 98 RON and in the past SU/L was 98 but is now 97 RON in this country?
Then again my knowledge of skylines is very poor but this is what applys to some modern cars that were only degsined around unleaded, but I've seen some cars run aviation fuel at 105 RON so who can tell?
I've wondered the same thing, leaded petrol killing the lambda sensor, but 4 star is now LRP - no lead in it. Whatever 'chemical cocktail' has replaced the lead - will it still have the same effect ???
I used the odd tank of leaded 4* a few years ago in my R32. I started to use it more and more as S/UL was not widely available and at the time about 7p per ltr more. Then LRP followed. It was good for octane but I started to get more and more lumpy running. In the end I needed 2 new (well second hand to be precise) air sensors. I then ran only on S/UL on the advice of Abbey and have had no problems since. I would say DON'T run on LRP at any cost. If you get "caught short" of S/UL then fill with UL and DRIVE CAREFULLY, ie not too much of a heavy right foot.
BTW try Shell's new Optimax S/UL....it seems to be the same price as their old S/UL (In W.London anyway) and after a few tankfulls, one of which together with octane booster powered me round Kemble, the car seems smoother and more responsive
I contacted Shell and they were very precice in telling me that Optimax is 98.6 RON and that it is not in a price promotion at present, and it will be marketed at the commercial S/UL price in each area.................A must I think
Hope this helps
You just saved me the hassle of asking yet another stupid question...was driving past my local Shell garage and saw all the Optimax posters . All I need now is my car ! Here's to a long 6 weeks of waiting.
I'd second the sentiments about using U/L rather than S/U/L. I didn't join this forum early enough and was running on the unsupped juice for too long, add to that regular serving by Nissan and voila...engine rebiuld . Believe me Stu it aint cheap but definately worth every penny