should i thicken my 30wt oil?

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Jun 21, 2004
ok, so im about to run mobile1 10w30. Ive been reading these forums alot, and ive read a few times the mobile1 is a very thin 30wt, or a thick 20wt. Now, i have a series II 3800 engine, the n/a version, ad i was thinking, if i will be keeping the oil in my car for 6 months (which is about 5,000kms)should i dump in one litre of 15w40 or 30, whichever the race oil is to thicken up the oil a bit, or should i add a litre of amsoil 10w30, since i heard that oil thickens to a 40wt after a while? need some suggestions pretty confused.
I don't like mixing brands or formulas, but Mobil says it is ok to mix. I assume that is why most 30 weights are formulated thin, because you are supposed to thicken it. Anyway, 1 or 2 qts of Mobil 1 15w-50 added will do you well. Maybe 1q in winter and 2q in summer. I would just use the 5w-40 SUV oil myself.
I would just run the Mobil 1 10w-30 and leave all the "mixing" to the people that make the oil. Any SAE 30wt oil is just that, a 30wt oil. Unless your manual prohibits "THIN" 30wt's, you'll be fine. Darryl [Cheers!]
When I ran Mobil1 5w30 and 10w30 in my 3800 series 2 it had some lifter noise.With Amsoil 10w30 it doesnt.So if i ran Mobil1 again i would do 4 quarts of Mobil1 10w30 and 1 quart of Mobil1 15w50.Then if makeup oil was needed i would use the 15w50 as make up.Just my opion.
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