Stay with the same brand of oil thru-out the life of the engine?

[derekslife]

I was reviewing the owner's manual for my engine (Westerbeke 82b) and ran across an interesting statement.

"For recommended oil, use SAE 15W-40 (oil viscosity) and stay with the same brand of oil thru-out the life of the engine. "

Perhaps this is due to different oil additives reacting with each other in a negative way?

How serious of warning is this?

What would be the impact if the engine has been using Delo 400 for the last few years, but then it was switched to use Shell T5 on the next oil/filter change?

Thoughts?

[a64pilot]

Nothing, same brands of oil is not a bad idea, nothing bad will happen if you stay with the same oil, but nothing bad is going to happen if you change.
For example, most all of us that buy a used boat have no idea what oil was used when we bought the boat, we change to our favorite brand and nothing bad happens.
I run Rotella myself, mostly because it seems to be the most widely available brand there is, but if I couldn’t get Rotella and I could get Delo and my oil needed changing, I’d happily go with the Delo.
I wouldn’t go with some strange house brand if I could avoid it though.

Example the actual manufacturer of many OEM oils, like Ford, GM, Yanmar will change from year to year depending on how often the contract is open, they submit bids to the major manufacturers with a list of specs of course and often go with who is cheapest, cause none of them actually refine their own oil.

[Lepke]

Originally Posted by a64pilot

Example the actual manufacturer of many OEM oils, like Ford, GM, Yanmar will change from year to year depending on how often the contract is open, they submit bids to the major manufacturers with a list of specs of course and often go with who is cheapest, cause none of them actually refine their own oil.

ditto

[capt jgw]

I was taught that you could change oil brands after an oil change, but you should stay with the same oil until the next change. (My dad was an oil distributer, so of course it was his brand we used). I'm not so sure that's correct, if the oil you're adding is the same standard as what's in there, it should be fine. And as mentioned above I wouldn't trust some stores house brand in my boat engine. Lawn mower, ok, but not the diesel.

[derekslife]

Thank you for the advice and thoughts!

[coopec43]

Originally Posted by capt jgw

if the oil you're adding is the same standard as what's in there, it should be fine.

I agree. A technical guy from an oil company said in the old days when oils varied from oil company to oil company it was not a good idea but these days it is not a problem. Of course car manufacturers would build a motor with a certain oil specification in mind so oil companies will use that as a standard.

[RaymondR]

SAE stands for Society of Automotive Engineers and there is a set of standards and probably recommended practices which were compiled and published by the society.

API stands for the American Petroleum Institute and they similarly produce a set of standards and practices for manufacturers to comply with.

The manual for your engine should provide an SAE viscosity recommendation and an API group recommendation and provided you comply with these recommendations and the manufacturer is actually providing lubricants which comply then the brand does not matter.

Shell and the other larger companies with reputations to protect are the ones most likely to reliably comply.

[Chuck Hawley]

My guess is that the current generation of oil for both gas and diesel is so far superior to the oil that was available when the engine was built, that any high spec oil of the proper viscosity would be OK.

Chuck

[Ken Z]

I have read oil reviews and 15-40 delo exceeds better in viscosity and cleaners, Ive used it for years and no engine problems, pull your dipstick when engine is hot, no bubbles from delo, not the same with the others, dont know about syn. oil.

[tkeithlu]

Oil comes in two SAE/API series, "S" and "C". The initials refer to the type of ignition, "S" for spark (gasoline engines) and "C" for compression (diesel). The C series can take the pounding of a diesel engine, the S cannot. The letters after the C or S refer to a progressive test standard, so an engine that needs SE can take SG. Those have progressed since the 1970s to the point of being ridiculous. You'll find in your car's owner's manual a specification, but if your gas or your diesel engine is more than a few years old every oil on the market save those sold for old tractors will exceed the needs of your engine. Just don't put S in a diesel. Multigrade (5W-40, etc.) ratings for diesel oil are fairly new, and for awhile the word on the street was that diesels needed single grade, but that may have been based on people putting "S" multigrade where it should not be.

[Midnight Son]

Just when you thought everything was perfect!


https://www.equipmentworld.com/all-a...right-for-you/


For those lucky/cursed to have the newest diesel engines. Here is a bit more reading for you.


Cheers

[a64pilot]

One of the major differences in formulations of newer Diesel oils is that many Diesel engines are using exhaust catalysts etc now and those have to be protected, and some of the old Diesel formulations would kill a Cat just like lead in gas will.

Look at the definitions of all Diesel oils after CG-4
https://www.api.org/products-and-ser...l-c-categories

Notice also the new Diesel F category