Here's the situation:

A friend used Mobil 5W40 for the very cold weather he experienced in Canada, and because he could not find 0W40.

He came to the US to visit, we went to Walmart and he bought two 1.25 gallon jugs of Mobil 1 0w40.

He is worried about mixing synthetic oils of different viscosities: his diesel uses a little oil and will probably need a quart in another 500 miles.

He's wondering if the mixing of the two viscosities will hurt the oil mix and the engine.

Logically, to me, since they are all the same brand, I cannot see a problem.

However, I would like some info, some real data, not opinions.

The reason I believe as strongly in biodisesel is that I have seen the tests on their extra lubrication capability in tests.

I'd like to find someone who has data or real expertise about this topic.

Unfortunately my buddy Joe in Philly, a retired petroleum engineer, is off some place in Florida and he is not answering his phone.

Have not seen any other posts like that in this forum.

Anyone have references?

Thanks.

__________________
Strelnik
Invest in America: Buy a Congressman!

1950 170SD
1951 Citroen 11BN
1953 Citroen 11BNF limo
1953 220a project
1959 180D
1960 190D
1960 Borgward Isabella TS 2dr
1983 240D daily driver
1983 380SL
1990 350SDL daily driver alt
3 x Citroen DS21M, down from 5
3 x Citroen 2CV, down from 6