Castrol 5W/50 full synthetic. Higher levels of ZDDP than their other synthetics.

 

My car leaks quite a bit. I had been using Castrol 20-50 on recommendations that synthetics cause leaks. Then I learned that early synths did not have gasket swelling additives, but new ones do. So I tried Mobil 1 0-40W. Haven't notice any increase in leaking based on what I need to add to top it up once in a while.

I like the synthetic. Gives easy starts in the cold and maintains pressure when it gets hot. Not sure if it needs it all that much, but I'm using a ZDDP additive.

Good Luck

 

I have used 15W-40 diesel oil in all mine from the 2L engines and several other cars to my current 964.
The brand does not seem to matter. After using up a barrel of Kendall, the current is Exxon, but the next will be Shell because WalMart had it on sale.

 

Stop changing brands! The seals are conditioned by the oil, and suffer when exposed to different oil formulations and additive packages. I still have zero oil leaks on an original engine. I just stayed with what the PO used: M1 EP. Last I looked, "EP" still had the higher zinc phosphate content.

 

Mobil 1 15w-50, the good stuff, not the "Extended Performance" variant. Tried Brad Penn once but oil consumption was higher than normal, about a quart every 1K miles. With the M1 I had to add about 1/2 a quart at 2300 miles. Plus oil pressure seems better with the M1.

93 C2 with 117K miles and the motor hasn't been rebuilt.

 

I've been very pleased with Valvoline VR1 20w50, even in Houston's 100+ degree summer temps.