Marine oil vs. auto oil???

[wakemaker01]

What weight oil do the 2003 mercruiser 350 tow mag use?

[scoot18]

The way everyone feels about marine oil, is how i feel about how Synthetic oil and "Premium" gas is marketed. They cost more and there is no real benefit over conventional oil.

No offence, I just got a laugh out of it that in the same post you said "dont get ripped of" and "I use full Syn".

Well I don't think I'm getting ripped off, I get the 5 qt container of Mobil 1 at Wal Mart for $20. to $22. I buy the the 5 qt containers of Pennzoil for my cars and it usually runs about $12 to $13 I would prefer to buy Pennzoil brand in synthetic but I can't find it in the weight I want, so thats why I buy the Mobil 1. It's not quite twice the price of conventional oil not like a boat or engine co. branded oil for 8 to 12 $ a quart or whatever it is they try and sell it for. I guess when I think about it I feel the same way you do, I tell my customers all of the time that using synthetic they are just spending more money, the oil has some advantages, but I also tell them that I am the type of person that if I used it in my cars I would still change it every 3mo or 3k and in that case you are just spending more money. However the oil in the tige' gets changed usually only once a season there for I use synthetic. It still looks almost like new when I change it so I assume it is doing a good job. To each his own I guess, I merely mentioned the oil that I use since that was kind of what this thread started as, a question about oil.

[jsz]

What weight oil do the 2003 mercruiser 350 tow mag use?

I have a 2002 merc 350 and I use 40W. I was told by my boat mechanic that in warm weather there is no need for multi viscosity.

[jsz]

Thanks for the replies. I thought it might be close to 1/2 and 1/2 but with only one marine oil user here so far, it looks like good quality auto oil is the winner.

[dom w. forte]

We have used Kendall oil for over 50 years and it is a synthetic blend, we recommend due to our climate, change oil every 50hrs or 6 months and only use the manufacturer weight.

[lightning59]

My friend manages a boat yard and I buy Mercuiser oil,filters, impellers from him at a shade under retail. He will take my calls and walk me thru a DIY repair or maintenance issue. If I pay a little extra for Merc parts, so be it. I want him in business and there when I need him.

[IDBoating]

We have used Kendall oil for over 50 years and it is a synthetic blend, we recommend due to our climate, change oil every 50hrs or 6 months and only use the manufacturer weight.

Resurrecting this older thread....

The "manufacturer's weight" in my case (2009 PCM EX-343 engine) is 15W-40 GF-4/SM. Every 15W-40 oil I can find is diesel rated (C*, not SM or S-anything). All the GF-4's (and some GF-5's) are 10W-40, etc. I can't find all of the things PCM wants in a single can.

Ambient temps here in the summer are over 50F.

So... what do you recommend?

Thanks!

[dom w. forte]

Resurrecting this older thread....

The "manufacturer's weight" in my case (2009 PCM EX-343 engine) is 15W-40 GF-4/SM. Every 15W-40 oil I can find is diesel rated (C*, not SM or S-anything). All the GF-4's (and some GF-5's) are 10W-40, etc. I can't find all of the things PCM wants in a single can.

Ambient temps here in the summer are over 50F.

So... what do you recommend?

Thanks!

The diesel rated oil is what we use , and will work fine for you, I would still stay with the 15w 40 and a synthetic blend.

[whitlock87]

yes I do and oil cost difference is small in the overall scheme vs ruined engine. Marine engines work harder and run hotter frequently for longer periods. A belt won't cook the engine, wrong oil will. I'm sure otehr memebers will pipe in too.

Not sure about your boat, but my boat engine runs Much cooler that my truck engine.
My boat runs around 140f and my truck runs around 190f.

[IDBoating]

The diesel rated oil is what we use , and will work fine for you, I would still stay with the 15w 40 and a synthetic blend.

I tried NAPA this morning. Nothing in stock that strictly met the PCM requirements, but they called Pennzoil while I stood there and Pennzoil agrees with you. In their opinion, a CJ-4 diesel rated oil will be fine. I'd like to have PCM agree too, since technically I would not be complying with their manual and I don't want that used as an excuse to void my warranty.

I have sent a message to PCM, via their website's "Contact Us" page, asking if they agree. This is the second inquiry I have sent them about winterizing (the other was whether I should fog the cylinders of my CAT engine). They have never, ever responded to messages submitted in that way despite their website's promise that they will, but I'm still hopeful.

Thanks!

[IDBoating]

Digging around, I found this on Mobil's website:

>>From an engine performance viewpoint, the API CJ-4 oil should provide adequate protection. But this heavy-duty viscosity grade has a higher level of phosphorus than typical ILSAC GF-4/API SM oils designed for today’s light-duty trucks and cars. This higher phosphorus level can potentially shorten the life of expensive emission control equipment including the catalytic converter. We recommend you stick with the oil recommended in your owner’s manual.<<

...from:

https://www.mobiloil.com/USA-English...s_Engines.aspx

So it may work great in normal exhaust engines, but my in CAT equipped engine it doesn't sound like the best choice.

[Moki]

Only "Ralph Lauren" designer marine oil touches my boat engine sold at fine establishments. All of the dinosaurs that the oil is made from has been screened to ensure that they are purebred dinosaurs. I will never use an oil that can be sold at Walmart or Kmart.

For the record, I do use marine oil, but wouldn't have a heartache over using auto oil.

[IDBoating]

For the record, I do use marine oil, but wouldn't have a heartache over using auto oil.

I WANT to use automotive oil, but cannot find 15W-40 GF-4/SM oil. I can find the weight, or the rating, but not that rating in that weight.

Two solid sources - Dom and Pennzoil - have said diesel rated (CJ-4) oil is fine. But I'm concerned about PCM and warranty issues... their owner's manual is quite specific.

From the manual:

The following chart shows the recommended oil viscosity
for various ambient temperature ranges:
Prevailing Ambient Recommended A.P.I.
Temperature Classification & Viscosity
Above 50°F SAE 15W-40 “GF-4/SM”
Below 50°F SAE 5W-30 “GF-4/SM”

IMPORTANT: The use of oils which contain “solid”
additives, non-detergent oils or low quality oils
specifically are not recommended.

WARRANTY NOTICE: PCM Engines reserves the right
to refuse warranty on part(s) and/or engine(s) damaged
by using improper fuels and engine oils.

It's that last little blurb that makes me wonder. I've emailed PCM asking for clarification but (surprise!) so far, nothing.

[IDBoating]

Followup: We have a couple of threads running on this topic, but just so everyone gets the data I'm crossposting this update.

-----
OK, I now have six quarts of the proper oil. It comes with a story.

After calling every auto shop around, and West Marine, to no avail I started calling boat shops. Several said they just use diesel rated 15W-40 oils.

However, the MasterCraft dealer - one of only two PCM certified shops in the entire region - had more to tell. He said they are not satisfied using diesel oil in a gasoline application. They've only had their PCM certification for a very short time (they got it because they are also the Centurion dealer) and they are careful to toe the line when it comes to PCM's requirements. They could not find the proper oil anywhere, so "I'm not surprised you can't find it either."

To remain in compliance with PCM's specs, they contract directly with Mobil and have the proper 15W-40 GF-4/SM oil delivered in 55 gallon drums. The shop manager drained six quarts into a couple of containers and sold them to me for $30.
-----

So the proper oil IS out there. If you can't find it at retail, check with local PCM dealers and see if they're buying it in bulk. If they're not, ask them what they use. You might be surprised!

[Moki]

I am glad that you found it!