Oil Viscosity
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Joined: Jul 2009
Posts: 81
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From: Lafayette IN
Oil Viscosity
My recently purchased 1986 Corvette...134,000 miles, needs an oil change. Records show the previous owner went from 10w30 synthetic to 15w50 synthetic. In checking with him, he gave the reasons as: "Seems that the first thing to wear on small block chevys is usually the cam bearings. This can cause low oil pressure at idle. As per a blog I had read, most people raise the oil thickness to offset this on higher miles engines. Plus the thicker oil in general supports wider bearing clearances that are common on higher miles engines." I've my inclination is to go with the owners manual at 10w30. Any thoughts concerning better mileage, engine tolerances, etc.
Thanks Guys & Gals...Love the forum...
Thanks Guys & Gals...Love the forum...
Team Owner
Joined: Sep 2001
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From: Athens AL
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I would go back to 10w30 unless you had an oil pressure problem and can't dig into the engine right now.
Le Mans Master
Joined: Aug 2007
Posts: 8,735
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From: WV
Read this post , we just discussed this very subject.Some people see a idle pressure of 12 to 13 lbs and freak out, this is within spec, as is a 55mph cruise pressure of around 30 to 35 lbs....WW
http://forums.corvetteforum.com/c4-t...-pressure.html
http://forums.corvetteforum.com/c4-t...-pressure.html
Last edited by WW7; Aug 17, 2009 at 03:51 PM.
Team Owner
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From: Riverside County Southern California
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10W30 
I used that for my 92 with 195,000 miles. Many others have higher mileage and still use 30 weight
I used that for my 92 with 195,000 miles. Many others have higher mileage and still use 30 weight
Team Owner
Joined: Dec 1999
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From: Lacey WA RVN 68-69
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A 10W-30 synthetic will work fine with 135K miles on the engine. Be sure to use a good quality oil filter like a Mobil-1, K&N, NAPA Gold, or WIX. You can even go to a larger filter like a Mobil M1-302 or AC Delco PF1218 or equal.
Team Owner
Joined: Mar 2001
Posts: 54,124
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From: Cincinnati, Oh USA
Why wouldn't it be, GM says to use 5W30. I have used 10W30 for every Corvette I have ever owned (64,69,74, and now an 87) and the first two had over 100k and the last two over 200k miles with original engines that didn't burn oil and with no engine problems. If you have reasonable oil pressure, then you don't need special weight oil. If you have unreasonable low oil pressure you should find out why instead of using higher viscosity oil.
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From: High Bridge New Jersey
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My recently purchased 1986 Corvette...134,000 miles, needs an oil change. Records show the previous owner went from 10w30 synthetic to 15w50 synthetic. In checking with him, he gave the reasons as: "Seems that the first thing to wear on small block chevys is usually the cam bearings. This can cause low oil pressure at idle. As per a blog I had read, most people raise the oil thickness to offset this on higher miles engines. Plus the thicker oil in general supports wider bearing clearances that are common on higher miles engines." I've my inclination is to go with the owners manual at 10w30. Any thoughts concerning better mileage, engine tolerances, etc.
Thanks Guys & Gals...Love the forum...
Thanks Guys & Gals...Love the forum...
