I have an 2002 Silverado that had a rear main seal leaking quite a bit. The truck is the most reliable I've ever owned. 340k and runs great and has been close to perfect. I have always ran 5w30 synthetic but the last oil change I filled with Valvoline Semi Synthetic High Mileage 5w30. The rear main has all but completely stopped leaking. I have been told that those motors were supposed to get full synthetic. Does it really matter if I keep my oil changes to 5k or so?
2002 4.8L Chevy - 5k oil changes?
- Thread starter Sealbilly
- Start date
I would buy you lunch the vehicle didn't leave the factory with full synthetic in 2002. synthetic blend will have no issue pulling off 5,000 miles that's an easy engine.
Thank you
Thank you.
CleanSump
Site Donor 2026
No problemo. Most manufacturers weren't even requiring synthetic oil in '02.
Japanese
$50 site donor 2026
That's great that the semi synthetic oil stopped your rear main seal leak.
However, if you want to keep your 5K oil changes I would step up to full synthetic. Valvoline Restore and Protect. It most likely will keep your rear main seal intact as well. People already reported that. Also, I run Valvoline Restore and Protect and it stopped my rear main seal leak which it was like .5 oz daily.
The thing about semi synthetic oils is:
1. We don't know know how much synthetic oil there is in them. There is no law to regulate that. It could be 5%, it could be 15%. But I think no more than that. It could be anywhere b/w 1% and 3% too.
2. The semi synthetic oils are closer (much more) in properties to conventional oils than synthetic ones. Because of the first part above.
So, if you respect your engine enough, I wouldn't run semi synthetic oil more than 3,000–3,500 miles. Otherwise you are risking to sludge and varnish it.
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CleanSump
Site Donor 2026
Peeve alert: "intact"
Those were the “Use an oil that meets 6094M spec” days…
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