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Re: Confused about which oil weight to use
Posted a similar thread on "Bob is the Oil Guy". Amazing how varied the responses have been.
One correction to my original post: Here is what the manual actually calls for:
<50F: 10 or 20 weight
50F - 60F: 20 weight
60F - 95F: 30 or 40 weight
>95F: 50 weight
Based on my research, and forum responses that seem well reasoned, I need an oil with an hot viscosity of 40 or 50, and a cold viscosity as low as possible (for ease of starting and initial start flow). Something like 15w40 in conventional, or 5w40 in synthetic. Pretty much confirms what most people recommend.
Back to the original topic.... I've been using Shell Rotella 15w40 for 35 years in all my diesel and most of my gas engines (old school low rev type). Only in the very coldest part of winter do I use a 10w30 but then the temps are low enough that its rather hard to sail in unless its an ice boat.
Its my understanding from a local ag and desiel repair outfit that in recent years there have been changes to Rotella T and it may not be as good as it used to be... Something about the Chinese (imagine that!) now manufacturing, but I haven't been able to verify that as yet. He will not use it anymore and is a Dodge Cummin fanatic, but works on any diesel. Like me he swore by it for years. I haven't changed out from it yet and trust me I will if needed.
Good luck on your cooling issue.
1980 Seafarer Swiftsure 30
1978 Bayliner Buccaneer 270 (now sold and being restored in FL)
1962 SeaMac 14' Plywood Runabout, mahogany decked, with 1959 Evinrude 35 Big Twin (owned since age 17, I'm now 60)
Last edited by dem45133; 08-03-2013 at 05:15 PM.