oil recomendation Malibu Boat 5.7 Indmar, please

[OILDummy]

I have a new to me 2000 Malibu Wakesetter 2400 lb port injected ski boat with a 5.7 Indmar engine with 350 hours. Indmar (in 2000) recommended Pennzoil marine 15W-40, API SL/SJ/CI-4, CH-4, CG-4.

Preferring synthetic, I was considering running Rotella T-6 5W-40, CJ-4, CI-4 PLUS, CI-4, CH-4, CG-4/SM. This oil indicates it compares to conventional sae15w-40.

Is this a good choice for a ski boat? Is the 5-40 difference an issue or OK? The boat will never be used in temps below 60F. The T-6 isn't a "marine oil", but appears more advanced? Agree??

 

[Donald]

I am not familiar with Indmar, but a 5.7 means its probably built on a GM block. If I were you I would use a 15W40 oil, Rotella makes one and Amsoil makes a synthetic one. You probably don't put on enough hours each year to warrant synthetic oil. And given that its a ski boat you probably use it only in warm weather, so the temp swing is small.

 

[OILDummy]

350 GM block, PFI. Plan on about 50 hrs an oil change.

 

[Bluestream]

If you won't see below 60F then I would run a good 30W HDEO, or the quicksilver 25W40 if you want to pay the money. Those engine are always under load, and have high oil temps and can shear a normal multi-grade down very quickly

 

[ledslinger]

Indmar recommends (and uses at our factory) Pennzoil Marine 15W40 Motor Oil. If Pennzoil 15W40 Marine Oil is not available in your area, we suggest using 20W40 or 20W50 oil meeting the API specification of SJ/CG4 or better.

Synthetic oil that meets our requirement of 15W40and API rating of SJ/CJ4 is acceptable to use after 100 hours or operation with the recommended (not synthetic) oil. The use of synthetic oil does not alter the requirement for oil changes at 50-hour intervals.

Older operator manuals, and other publications that are not regularly updated will not be revised to show this latest engine oil recommendation. Current operator manuals, and other service publications that receive regular updates will receive this revised recommendation the next time they are updated.

Here is info from Indmar's site. I am a marine mechanic that specializes in ski boats. I use mainly HDEOs 15-40 or straight 40.

 

[OILDummy]

Thanks for your input, it appears the T-6 3-40 would meet these requirements.

 

[Donald]

I have a 5.7L Mercruiser and use the Shell Rotella 15W40 oil. Its a very heavy duty diesel rated oil. I guarantee my engine is under a much heavier load given its pushing a 24' express cruiser.

 

[ledslinger]

Donald- You are right about your boat loading the engine more. Ski boats don't load continuously. Short runs at wide throttle openings is what they see.

Older ski boats with about 250 HP used to work pretty hard for Men's slalom or tournament jumping, but with 340 HP they mostly loaf. But I suppose the demands on the oil are similar and based on load and power and not throttle opening.

 

[Steve S]

For 50 hours a non syn will be all that is needed. I really doubt you will see a difference between syn and conventional oils .