Mobil 1 Extended Performance 15w-50

[Oldman]

Has anyone had experience using , or opinions on Mobil 1 Extended Performance 15W-50 in GTR's? A mate of mine runs it in a 928 Porshe and swears by it. Any opinions on how it would rate against Castrol R 10w-60 ?

[Roy]

I forsee 20 posts all with different opinions. Motul will no doubt be mentioned etc.

My thoughts are if its good quality oil, its changed regularly, and its not cooked with sustained high temp use, then you are ok. I use to love the Mobil 1, but the viscosity i use to use in Sydney isnt available in Vic, so i now use Castrol R 10w-60.

Just keep in mind his car is an NA V8, so the oil isnt likely to see the revs and heat that your GTR will, so wouldnt try and get the same life out of the oil as he would in the Porsche

[Busky2k]

M1 EP is a very good oil as it contains roughly 30% more detergents and antiwear additives compared to the regular M1 formulation. I would recommend it over the Castrol R with no hesitation. And there simply would be no point changing it out any earlier than 10,000kms (as its rated to last 15,000 miles!) IMO the 10W-60 is too thick. It belongs in a smoke blowing sigma.

[Roy]

If its an improvement over regular M1 then great. My old RB20 bottom end is in great nic, and the head was very clean as well after 160,000kms. so the oil is certainly good at cleaning, lubriocating and cooling an engine that saw plenty of track use with no oil cooler.

I seem to recall reading somewhere that the M1 was also one of the mroe stable high temop oils...but to say the Castrol R is too thick...well again my temps get pretty high when im at the track, especially considering im making 130% more power then std with tstock coolign / oiling...so the extra viscosity is insurance in my eyes, and hopefully will help the bottom end hold together.

Again horses for courses, and not disagreeing with you regarding Mobil1, but i would still be a little reluctant to keep any oil for 10,000kms especially if the GTR is driven hard whenever its taken out, and struggles to cover 10,000kms in less then 6 months...

Like i said, just some thinking, not really disagreeing

[Busky2k]

No problems Roy. Everyone is entitled to their own opinion. I too would run Castrol R 10W60 if the car is used regulary on the track, to counteract the thinning of the oil as the oil temp soars. But if the temps are regularly over 130C, I would recommend an oil cooler

As for 10,000ks, the best thing to do is an oil analysis. That way monitoring aspects such as fuel dilution, wear metals and TBN can truely give you an indication of how long an oil can stay in an engine. Again, if the car is track driven, 10,000ks is too much as it would be loaded with soot from blowby and fuel diluents (from rich running).

For a pure street car, 10,000ks on M1 should be no problem.