What (Specifically) makes GC good for extended drains

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Jan 16, 2003
Shippensburg, PA
Ok... here is what I know (or at least what I THINK I know [Wink] ). 1. GC base oils are very viscosity-stable 2. GC base oils are very oxidation-resistant. 3. GC has a robust additive package. Now... the $1 mil question: What component(s) of GC provides the dispersant / detergent abilities and TBN retention to enable GC to deal with thousands of miles of combustion by-products, moisture, etc? I am still trying to make myself feel comfortable with extended drains, and I'd like to know what components are working to keep my engine protected and sludge free over a long interval. IMO, Great base oils are one thing, but how does this really help keep combustion by-products "in check"? I am using GC, and we know a lot about it, so I figured maybe one of the chemist types could point to specific additives and give me a lesson. [Smile]
I thought the consensus here was that GC's extended OCI capabilities are rather limited. Some people agree that it handles 10k miles rather well in certain engines. What OCI length are you talking about? I’ll run a sample after my 6k miles interval.
I can't answer your million dollar question, but the only way to make yourself comfortable with the extended drains is to do them and get a UOA to show you everything is ok. I was a die hard 3000 mile OCI for almost 20 yrs, just recently decided to try. I went 7500 miles on GC and everything tested fine, was told to try 10,000 next time (can't, warrenty reasons). I am now trying RP for 7500 miles to compare the two.
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