What Oil Should I Use?

[Fanny]

I have a 1990 Chevy Suburban (8-cylinder, gas), and I’m in a bind trying to decide if I should use either 5w-30 or 10w-30 oil.
I’ve lost the owner’s manual and the oil cap says to use 5w-30, but the person who gave me the suburban is claiming that it’s an oil cap from a different vehicle and that I must use 10w-30. She’s not very bright and is the sort of person who likes to pretend she knows everything–a real Peggy Hill sort of person.

It’s got 230,000 miles on the engine, so I’m sure it’d be best to use synthetic oil. Though seeing as it’s more expensive, I’d rather not waste money on oil that may damage the already frail engine.

Any feedback is welcome!

Please forgive my dyslexia.

Topic

[Dave]

With that kind of mileage it doesn’t matter what viscosity of oil you use just do not use synthetic in it now.

[college man]

10w-30 will do it.

[kevin gosselin]

I would stick with 10w30 and may consider 5w30 in cold weather condition… under 10 degree celcius as regular climate… if you don’t see snow… stick with 10w30… no need of synthetic

[Author]

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