What oil to use in older Mercruiser engine.....changing engine oil

[Jim Robbins]

I have a 140 HP Mercruiser (ser.# 3129102 (1971 or 1972 ?) and the old manual said to use a
SAE 30 / API Class. MS or SD *what does the MS or SD mean?
I should use a SAE 30 weight oil that is a Nondetergent type - correct?
(I boat in Lake Huron (fresh water)
When changing the oil, have cooling water flowing through wp, start up the engine

(do I use an engine flush to help loosen up any sluge OR drain oper. temp. oil then add fresh oil, start up to temp. and drain again ?)
run engine up to opperating temp, drain oil.
Change oil filter (coat of oil around sealing ring, tighten securely by hand) fill crankcase with proper amount of oil, run engine a few mins. check for oil leaks, shut down wait a few mins and check dip stick (add more oil if needed). Anything I missed or any advice?

 

[HT32BSX115]

Re: What oil to use in older Mercruiser engine.....changing engine oil

Howdy,


I knew if I waited long enough SOMEONE would start an oil thread!!

I have a 140 HP Mercruiser (ser.# 3129102 (1971 or 1972 ?) and the old manual said to use a
SAE 30 / API Class. MS or SD *what does the MS or SD mean?
I should use a SAE 30 weight oil that is a Nondetergent type - correct?

1. NEVER USE NON-DETERGENT oil in ANY thing (except maybe to lube your squeaky door!!)

2. Use what Mercruiser suggests in their current guidance.

Right from mercruiser:

What type of oil should I use? Can I use synthetic oil?

Engine Oil
For optimum engine performance and maximum protection, use the following oil:
Application Recommended Oil All MerCruiser engines Mercury MerCruiser Full-Synthetic Engine Oil, 20W-40, NMMC FC-W rated IMPORTANT: Lubrication requirements for catalyzed engines differ from the requirements for non-catalyzed engines. Some marine-grade lubricants contain high levels of phosphorus, which can damage the catalyst system on MerCruiser engines. Although these high-phosphorus lubricants may allow acceptable engine performance, exposure over time will damage the catalyst. Catalysts damaged by lubricants containing high levels of phosphorus may not be covered by the MerCruiser Limited Warranty.
If Mercury MerCruiser Full-Synthetic, 20W-40 oils is unavailable, use the following lubricants, listed in order of recommendation. If you are servicing a catalyst engine, use these for short periods of time only.

1. Mercury/Quicksilver 25W-40 Synthetic Blend, NMMA FC-W-rated 4-cycle MerCruiser oil
2. Mercury/Quicksilver 25W-40, NMMA FC-W-rated 4-cycle MerCruiser oil
3. Other recognized brands of NMMA FC-W-rated 4-cycle oils
4. A good-grade, straight-weight detergent automotive oil according to the last row of the operating chart below.

NOTE: We do not recommend non-detergent oils, multi-viscosity oils (other than as specified), non-FC-W-rated synthetic oils, low-quality oils, or oils that contain solid additives.

This crankcase oil recommendation supersedes all previously printed crankcase oil recommendations for MerCruiser gasoline engines. The reason for this change is to include the newer engine oils that are now available in the recommendation.
Older Operation, Maintenance & Warranty manuals, Service manuals and other publications that are not regularly updated will not be revised to show this latest engine oil recommendation. Current Operation, Maintenance & Warranty manuals, Service manuals and other service publications that receive regular updates will receive this revised recommendation the next time they are updated.

Now this thread will probably morph into a "This is what I use and have never had a problem........"

You'll find that every oil has been tried successfully.

It's true. Use whatever you want. (except API SA oil [non-detergent])

what does the MS or SD mean?

( Actually it's SM/SD)

It's explained in the following link. So you'll have to do a little reading.....

http://new.api.org/certifications/engineoil/categories/index.cfm

(do I use an engine flush to help loosen up any sluge OR drain oper. temp. oil then add fresh oil, start up to temp. and drain again ?)

Oh, another "NEVER"...........NEVER flush an engine using a solvent!! It can break particles loose that could end up in an oil passage that supplies a rod or main bearing. If you starve a bearing, the results could be catastrophic!!

Regards,


Rick

 

[ttugrad]

Re: What oil to use in older Mercruiser engine.....changing engine oil

+1, with one exception: non-detergent oil is great for air compressors.

 

[HT32BSX115]

Re: What oil to use in older Mercruiser engine.....changing engine oil

+1, with one exception: non-detergent oil is great for air compressors.

That of course would depend on where the "air" is used. In some cases motor oils might be bad for a compressor..... (breathable air compressors)

Campbell Hausfeld for example DOES suggest using (their) non-detergent oil for one of their big oil lubricated compressors.........but they also allow Mobil 1 (which IS a detergent oil!!)

From Campbell Hausfield operating instructions for their cast iron series compressors:

Fill pump with single-viscosity, ISO100, non-detergent, compressor
oil. Use part number ST126700AV com-
pressor oil or Mobil 1? 5W30 or 10W30
synthetic oil may also be used.

 

[ttugrad]

Re: What oil to use in older Mercruiser engine.....changing engine oil

I stand corrected...

MY air compressor (Craftsman Professional) requires the use of non-detergent oil. I don't have any user manual quotes to prove it though.

Ladys and Gentlemen, this is the perfect example of a thread hijack! My fault!

 

[HT32BSX115]

Re: What oil to use in older Mercruiser engine.....changing engine oil

Ladys and Gentlemen, this is the perfect example of a thread hijack! My fault!

Yeah.......

No one seems to care though!

 

[Joshua Nichols]

Re: What oil to use in older Mercruiser engine.....changing engine oil

I knew if I waited long enough SOMEONE would start an oil thread!!

You have to admit.. It's been awhile.. Like a week or 2

 

[HT32BSX115]

Re: What oil to use in older Mercruiser engine.....changing engine oil

You have to admit.. It's been awhile.. Like a week or 2

Yeah. I was beginning to think there might be an "Oil Thread filter" that automatically moved them to the "Oil Thread Forum!!"

 

[Don S]

Re: What oil to use in older Mercruiser engine.....changing engine oil

Go to the last page of this forum, and look at the posts on the bottom of the list.

 

[nola mike]

Re: What oil to use in older Mercruiser engine.....changing engine oil

2 exceptions: I have a moped that uses non-detergent in the tranny.

 

[elkhunter338]

Re: What oil to use in older Mercruiser engine.....changing engine oil

You can also run a 30 weight diesel grade oil and be fine, most boating is not done in cold temperatures and a standard 30 weight is ok.
My new engine manual says SAE 30 for temps below 70deg., this is a 2007 manual that came with my factory new 3.0L.
I run chevron delo 400 SAE 30.

 

[Chris1956]

Re: What oil to use in older Mercruiser engine.....changing engine oil

I always like the MerCrusier (actually Quicksilver) 25-40 motoroil. I felt it gave a thinner viscosity(SAE 25) for those cold weather starts plus the SAE 40 weight protection for warm weather and warm motors.

 

[edboater111]

Re: What oil to use in older Mercruiser engine.....changing engine oil

Thanks to all who q/a here!!! MANY problems solved in one quick reading of your threads!