RodGrp

I was wondering guys, should I use synthetic 10,000 miles or stick with conventional oils. My brother says stay away from synthetics and switch the oil 20W-50. The reason was 5W-30 is used for high altitude and he is mechanical engineer. This is my first new car and won't it to last for a long time. What do you guys think. I just had my oil change and starting at 5000 miles.

Mean Gene

Rod - Not sure where it is but we ran the synthetic vs conventional deate in an old thread here in the Maintenance forum. I'm a petroleum engineer & live in hot/humid Louisiana & don't see the need for 20W/50 oil. I've run 5W/30 in both my GS & an old Lingenfelter 600 HP 'Vette with no problems. I'd stick with the factory specified viscosity. Be sure & check back a few pages for that thread I spoke of. BTW - I'm a Mobil 1 man all the way ( I don't work for Mobil, however ).

iluvlex

I'll have to second that Mobil 1 comment.

chowder

so 5W/30 like the manual says is "preferred" viscosity -- that's what you use? i was damn close to putting in 10W/30 mobil 1 this fine afternoon...
can you tell me where the 5 vs 10 becomes an issue?
thanks.

iluvlex

Unless you're going to travel cross country through the dessert use 10w-30... otherwise 5w-30 is preferred and will flow better.

Yes, I use Mobil 1 Tri-Synthetic 5w-30 on a 92'SC4. Very good stuff

Mean Gene

Chowder - Actually, the 5 means that the oil will behave as a 5 weight oil when cold ( it will flow easier when cold ) & then as the oil will take on maximum characteristics of a 30 weight oil as it heats up. It just gives better flow characteristics at start-up that a 10W-30. Lexus recommends it because of the slighly wider range of viscosity over the 10W-30 ( better pumpability when cold ).