Oil weight question, Chevy 5.7

Robert D

Petty Officer 1st Class
Joined
Feb 21, 2009
Messages
338
Have a 1990/1991 Chevy 5.7 marinized by a Yamaha Marine shop.....seems to have all Mercruiser parts, including valve covers, exhaust, etc. Label on the oil filler tube says to use SAE 40 for the engine.....doesn't this sound a bit thick for using in a late model engine????
 

HT32BSX115

Supreme Mariner
Joined
Dec 8, 2005
Messages
10,083
Re: Oil weight question, Chevy 5.7

Have a 1990/1991 Chevy 5.7 marinized by a Yamaha Marine shop.....seems to have all Mercruiser parts, including valve covers, exhaust, etc. Label on the oil filler tube says to use SAE 40 for the engine.....doesn't this sound a bit thick for using in a late model engine????

That would be correct for that year. Oil has gotten better though and Mercurys' recommendation is below.

From http://www.mercurymarine.com/servic...ntenance/faqs/mercruiser/?category=fuel#MCOil

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:
ApplicationRecommended Oil
All MerCruiser enginesMercury 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.
oil%20chart.gif
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.


Since the "Yamaha " engine is the same as a Mercruiser, you would absolutely be correct using Mercurys' recommended oil if you didn't want to use what Yamaha suggests using.

Otherwise, do a search here. EVERY type of oil has been used successfully.

It's not as important what type you use........It IS important that you change it regularly and at the end of the season before you let it sit all winter etc.

regards,




Rick
 

Robert D

Petty Officer 1st Class
Joined
Feb 21, 2009
Messages
338
Re: Oil weight question, Chevy 5.7

Sounds good! Sorry for the wrong section....I missed the word 'outboard' in the forum title :)
 
Top