At the risk of beating a subject that's been covered extensively in here, in the April EXCELLENCE, in his article on "Oil Coolers...", Jim Pasha states that for 1989 and later 911's, he recommends Mobil 1; on the earlier cars, he recommends Valvoline Turbo or Kendall GT-1 because, in his experience, "they are the best heat-resistant oils on the market." He goes on to say that both these oils have zinc and other heat-retarding additives, which at high temps,lubricates and supports the bearings; it (the zinc, I presume) also helps prevent camshaft lobe wear (for cars that idle a long time in traffic), and helps valve guides last longer. He says that in Turbo engines, these oils also resist "coking" (literally cooking the oil) in the turbocharger's oil feed lines. In my SC with the 28 tube cooler, my temps have been well within the accepted ranges during "normal" driving conditions (t-pike as well as city traffic). HOWEVER, at certain DE events (usually dependent on ambient temps at the track), I start to run hot (over 240). I've used Mobil 1 exclusively because I understood it to be heat resistant and less prone to oil breakdown at higher temps. Has anyone with an "older" 911 (say, Carrera and earlier) used either of these 2 oils, and found their cars to run cooler than with Mobil 1? Thank you in advance...

 

My take on the article was that these 2 conventional oils are the best of the conventional oils,not better than Mobil 1.Having said that I believe he was also stating that he believes that pre 1990 Porsches should run conventional over synthetic,not sure of all the reasons.The opinions on this are split,some guys swear by conventional and others to synthetic,what ever you feel comfortable with I guess.I don't think either of those oils is going to run cooler than Mobil 1,but they may run cooler than other dino oils because of the zinc content.For what its worth,I run Kendall 20w50 in my 83SC.

 

I haven't used any of the oils mentioned but I have for the last 18 months been using Castrol Magnatec in my '78SC I haven't noticed a change in oil temps but my car hardly emits a puff of smoke on startup now (like me it's never been a heavy smoker)
At 144,000 miles it feels tight and I swear there has been a just 'feelable' bhp gain . Could be kidding myself , though I do notice a slight bhp gain when using Shell Optimax petrol (I don't know if you have a U.S. equivalent of this) . I also use Magnatec gearbox oil and this has helped a slightly 'notchy' first gear operate smoothly .

 

john,
i read that article as well with interest.
my car has run Castrol GTX since new and no problems with high temps ever. i've thought about changing to Mobil 1 cause everyone raves about it - but figured why stop a good thing.

have always used 20w-50.

Maurice
1980 SC Coupe