Which Engine Oil Do You Use (& Why)

[MarkSF]

Synthetics HAVE been reported to attack seals, but those reports are wrong. What happens is that someone substitutes a 5w40 synthetic for a 15w40 non-synthetic, and, guess what, it leaks through the old engines dodgy seals much faster when the engine is sitting.

I've put synthetics in older engines and had no problems, but they weren't leaking oil to start with.

Synthetics (and blends) do have better properties than non-synthetics (particularly lifetime without loss of grade, and ability to withstand heat). The question is whether you are in a position to benefit from those properties. An old, low-revving diesel with no turbocharger, that has its oil changed every 100 hours? Synthetic is probably pointless.

On the other hand, put non-synthetic in my TDI car with a turbo and 10K mile service interval, and you would be making a VERY expensive cost-saving. Ask VW about that, they had terrible issues with sludging 1.8T engines in the older Passat, as a result of US dealers putting in poor-quality oil instead of the required synthetic.

[Stu Jackson]

Originally Posted by MarkSF

Synthetics (and blends) do have better properties than non-synthetics (particularly lifetime without loss of grade, and ability to withstand heat). The question is whether you are in a position to benefit from those properties. An old, low-revving diesel with no turbocharger, that has its oil changed every 100 hours? Synthetic is probably pointless.

Very good points, thanks for the reminder and the qualification.

[Cheechako]

Delo my oil of choice followed by Shell Rotella. I found Rotela more available in the Caribe so switched to that.

[zboss]

We use rotella 30 straight weight in our 27 year old westerbeke because it has such a good reputation and availability.

[jcapo]

Rotella T1 40w, Yanmar 4JH-DTE, cuz I can get it anywhere.

[Dockhead]

Originally Posted by MarkSF

Synthetics HAVE been reported to attack seals, but those reports are wrong. What happens is that someone substitutes a 5w40 synthetic for a 15w40 non-synthetic, and, guess what, it leaks through the old engines dodgy seals much faster when the engine is sitting.

I've put synthetics in older engines and had no problems, but they weren't leaking oil to start with.

Synthetics (and blends) do have better properties than non-synthetics (particularly lifetime without loss of grade, and ability to withstand heat). The question is whether you are in a position to benefit from those properties. An old, low-revving diesel with no turbocharger, that has its oil changed every 100 hours? Synthetic is probably pointless.

On the other hand, put non-synthetic in my TDI car with a turbo and 10K mile service interval, and you would be making a VERY expensive cost-saving. Ask VW about that, they had terrible issues with sludging 1.8T engines in the older Passat, as a result of US dealers putting in poor-quality oil instead of the required synthetic.

Cars are very different from marine engines. Synthetics are not just pointless, but can be very harmful to marine engines. I suggest reading the article linked in the OP.

You should use exactly the grade of oil specified by the engine manufacturer, and nothing else. You may think you're doing your engine a favor by using a "higher" grade of oil than what it was designed for, but you are not. A little reading on the subject can be very beneficial.

[Arthur Garfield]

2 Cents- Older engine Rotella T.New engine synthetic.Naturally aspirated or not.
Warmer climate,usual extended running times or normal running at higher RPMs-
20-50 wt..

This experience from running numerous diesel vehicles,machines and vessels.

Certainly certain synthetics much much better for internal wear and turbo motors.Additionally,synthetics will give easily 500 hours on 150 hour filter changes.

[svHannabel]

Rotella T 15W40 in our Universal M25XPB diesel.

[rognvald]

Shell Rotella T--straight 30 Weight. Unless you are sailing in temperature ranges that very greatly from warm to cold, a straight grade oil, in my opinion, is always the best. Older engines with lots of miles should use a 40 or 50 weight depending on the average ambient temperature. I am not a fan of multi-grade(unless absolutely necessary) or synthetic oils.

[svHannabel]

Originally Posted by rognvald

Shell Rotella T--straight 30 Weight. Unless you are sailing in temperature ranges that very greatly from warm to cold, a straight grade oil, in my opinion, is always the best.

Fair enough. I only use the T Triple Protection 15W40 because that's what Universal recommends in the manual. Based on what you're saying, I should switch to Rotella T1 straight grade 30. Hmmm...I'll give it some thought.

[rognvald]

Originally Posted by svHannabel

Fair enough. I only use the T Triple Protection 15W40 because that's what Universal recommends in the manual. Based on what you're saying, I should switch to Rotella T1 straight grade 30. Hmmm...I'll give it some thought.

Hannabel,
I would use whatever engine oil is recommended for your engine in case there is a warranty claim or a premature mechanical failure issue. They might be prone to help you if you followed factory recommendations. However, most trucking companies that put millions of miles on their engines use a straight grade oil with a quality filter. Yanmar recommends a straight grade oil in my engine as do most marine mechanics for all engines. I have used straight 30W in the tropics as well as here in the Winter Wonderland. My engine has 2100 hours and when I pulled the head to do my valves, the pistons and cylinders looked literally new with no engine wear. I hope that helps. Good luck and good sailing.

[barnakiel]

Originally Posted by Wotname

Have you had any difficulty in sourcing a mineral CD oil?

I can't find it on the shelves at general retail outlets in Oz.- although as stated in the first post, I have sourced some from a specialised outlet.

Never a problem anywhere.

What about a visit to local commercial/fishing dock?

b.

[Hud3]

Shell Rotella T 15W-40 for our Yanmar 4JH3-BE.

[Wotname]

Originally Posted by barnakiel

Never a problem anywhere.

What about a visit to local commercial/fishing dock?

b.

Yes, good point, I will try that.

[Wotname]

Thanks every one for the input and please keep them coming

A rough picture is emerging but more input will define it better.

If you know, please add the API rating of your chosen oil - it saves me looking it up eachtime someone mentions a new oil that is not familiar with me. All detail is appreciated . For instance, if you mention say Rotella, also add which Rotella as there are many.

Interesting comment by Rognvald re single weight oils, I must read more...