Lesser of three evils...oil types in MX

[Controlled Jibe]

Hello, We have a Westerbeke (Bukh built) Pilot 10 down here in the Sea of Cortez. We cannot find anyone who sells the (manual recommended) SAE 30 (API C rating) motor oil in Mexico, and so we're left to choose from other alternatives. In the summer, air temps reach 110, and in winter the temps won't go below 55. The oils we have to choose from are:


Chevron Delo 15w-40, CI-4
Quaker State Series 3 SAE40 CF
Quaker State SAE30 SL

The question being: in this climate, are we wiser to stray from the recommended viscosity to stay with the C rating, or downgrade to the S rating to stick with the SAE 30 viscosity (especially in these somewhat cooler winter temperatures to come)?

Thanks in advance

[contrail]

I would use the Delo 15-40. It is a multigrade, so will be "thin "enough for engine starting when it is cold, and "thick" enough for when the engine is warmed up and it is hot. The Quaker State 40 weight won't be thin enough for the cold weather starting. Above all, don't use the Quaker State 30 weight! The S part of the rating (SL) stands for spark, as in a gasoline engine. The C part of the rating for the other two oils means compression, as in diesel. Don't use oil made for a gasoline engine in a diesel....the additives are very different.

[leftbrainstuff]

The short answer is any of those options will be suitable. Clean oil is better than old and dirty oil.

You could further prioritise your options based on the following questions:
1) does it start ok
2) how worn / old / tired is the engine
3) do you have any significant blowby or oil burning
4) how often do you run it and for how long

[leftbrainstuff]

Originally Posted by contrail

I would use the Delo 15-40. It is a multigrade, so will be "thin "enough for engine starting when it is cold, and "thick" enough for when the engine is warmed up and it is hot. The Quaker State 40 weight won't be thin enough for the cold weather starting. Above all, don't use the Quaker State 30 weight! The S part of the rating (SL) stands for spark, as in a gasoline engine. The C part of the rating for the other two oils means compression, as in diesel. Don't use oil made for a gasoline engine in a diesel....the additives are very different.

+1 for this poster

[Controlled Jibe]

Thanks everybody, that's the way we were leaning too, we just needed a little validation.