Hi.

I hope I'm not repeating any quetions that someone have already answered. I have searched the forum but didn't find anything.

My question is what grade engine oil should I use?

My car has 58k miles on it. In the summer time I use Mobil 1 10w-30 and winter 5w-30. Is that ok? The current temperature right now is ~10F and ~90F in summer.

The other question is some places say change your oil every 3k miles or 3 months. Why is it necessary to change the oil in 3 months if I only put 1k miles on the car?

I used to change it every 10k according to the FSS but since I find that unreliable I decided to change every 5k miles. Do I still have to change every 3 months?

Thanks for the help.

See http://www.whnet.com/4x4/oil.html. You should be able to change it once a year with no problems. Just my 2 cents.

Here is a link to a great life study of Mobile 1 vs. Amsoil

http://neptune.spacebears.com/cars/stories/oil-life.html

It is very comprehensive and seems to have been well researched and documented. My understanding of the highlights:

1) Most of the engine wear occurs in the first 3000 miles after a change...this was a big surprise.
2) Both oils seem to be good for well over 10,000 miles. Mobile 1 went 18,000 miles.
3) Amsoil has a severe viscosity increase that actaully affected fuel economy.
4) Amsoil seems to work slightly better in the engine wear department.

I would be very interested to see other opinions oof this test.

__________________
Litton
'90 420 SEL (sold)
'72 280 SEL 4.5
'98 ML320 (for sale)
'86 560SL
'05 Jeep Grand Cherokee Ltd (offroad in style)
'87 Chevy Blazer (AZ Pin Strips)