Originally Posted By: vincent714028
It's a 94 camaro v8. A shadetree mechanic put a used engine with 160000 miles in my car. He filled it with Castrol GTX 20w-50. I think that is too thick and would like to try a thinner oil like 5w-30 since that is what is speced for my car.
I don't want to waste this oil so would it do any harm to leave it in for 3-5000 miles?
20W-50 is probably the last grade of oil I'd use in any engine not on one of my lawnmowers.
The only reason the lawnmowers are getting GTX 20W-50 is that I had some left over from an old Mercedes we had, in which I used it during the summer, per the OM. My BMW specs a 20W-50 for the summer as well, but I don't think it really needs it, so I don't use it.
The old Mercedes would have probably been fine on 10W-40 as well.
Anyway, I'd run the oil 3-4K.
It won't do any harm.
You might then try a 10W-40 and if that works out, move down to a thirty grade oil.
These are tough motors, and 160K isn't all that many miles.
Even if the thing was run hard, as long as it had a reasonable oil changed on reasonable intervals, it will likely be okay.
What car was this engine out of, and why was a 160K car in the salt-free south scrapped so young?
Wrecked?