1985-1998 [Subscribe to Daily Digest] |
>> 8. If you are using fosil oil then stay with it or expect some leaks later on. You may consider a blend oil and get away with it.
A Road & Track magazine reader posed this question to their Technical Correspondence column some time ago. His car was an Eclipse with 72k miles having run Castrol GTX since new, and he wanted to switch to synthetic, but was worried about leakage. This is R&T's response:
"According to Chevron, the problem you cite of increased seal leakage was a concern a decade or so ago. Since then, The lubricant industry has added esters to synthetic oil to better match the seal-swelling characteristics of mineral oils. So, you should have no problems, but with the huge variety of oils avilable, Chvron could not give an ironclad guarantee that you would have no trouble.
"Besides seal-swelling differences with synthetic oils, some paperlike composition gaskets become quite hard with age and don't respond like syntheric rubber when interocued to syntheric oil. The difference is the aromatic compounds preent in mineral oil. Syntheric oils lack aromatics which are the primary cause of gasket softening and elongation (swelling), and their absence can occasionally result in slight leakage or increased leakage."
FWIW, I've changed to synthetic from fossil in my last three vehicles, two 9K's, the first at 25k (124k when sold) and my present Aero at 35k (now with 67k) when I purchased it, and a Harley-Davidson at 9K (now with 72k). None of these vehicles have exhibited any leakage of any kind, except the '91 9K, which developed a minor rear main seal leak at about 100k, but I doubt if this is a result of synthetic usage.
One more comment to Bryan, that Dick is the only person on this board I've seen that recommends a 0-30 oil year round, and it almost certainly would be too thin for hotter areas of the country in summer. Saab recommends a 10w30 except in very cold weather, but up to 20w50 can be used when temperatures don't go below ~55°F (ref: Saab service manual). I use 15w40 Royal Purple synthetic year round in Louisiana.
posted by 68.11.185...
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