oil

[major hattitude]

Hi everyone having hard time finding 40W oil anyone having luck also wondering if anyone
runs 15w40 any info greatly apricated

 

[Bob Quinn]

Napa has it.
NP75118

 

[Captain Ralph]

Napa has it.
NP75118

75118 is the CF2, 40w oil for Detroits.
75121 will fill the request for 15W40.

 

[cww]

Hi everyone having hard time finding 40W oil anyone having luck also wondering if anyone
runs 15w40 any info greatly apricated

Any napa, west marine, or truck stop will have CF-2 rated SAE40 or if they'll out of it they will order it and have it to you in a day or two. Any detroit dealer will also sell it (with a markup). You can't run multigrade oil in 2-stroke detroits it will shear down and result in scoring the liners and pistons. Schaeffer makes a full synthetic CF-2 that is good.

 

[Wilson]

Best price for Rotella T1 40 W is Tractor Supply. They will rain check a ny quantity for you..

 

[Tinker]

2 weeks ago I picked up two 5 gallon Pails from the local Napa and left two for the next guy. I like the Napa 71558. For whatever reason that is says it is for Detroit diesel two stroke make me feel better pouring it in. And yes I have enough oil, filters, and fuel filters for the next two oil changes on board. Must be what makes me slow.

 

[Sadey]

Just bought 40 gallons of Rotella 40W at Fleet Farm in Wisconsin. Why so much you ask? 13.99 a gallon. Why 40 Gallons? That’s all they had. The sale is to the end of October.

 

[Captain Ralph]

Hi everyone having hard time finding 40W oil anyone having luck also wondering if anyone
runs 15w40 any info greatly apricated

The OP spec'd 2 different oil types. Either way, NAPA has the best availability on both oil W's.

 

[Dragonten]

I buy mine a O'Reilly's they order it for me.

Thanks,

 

[cww]

The OP spec'd 2 different oil types. Either way, NAPA has the best availability on both oil W's.

True but his profile says he’s got a 53 MY, so the reality is he can’t use his 15W40 suggestion without causing engine damage.

 

[krush]

.......... You can't run multigrade oil in 2-stroke detroits it will shear down and result in scoring the liners and pistons. Schaeffer makes a full synthetic CF-2 that is good.

Explain this phenomena please. 2strokes have much tougher duty on liners/pistons? A modern high speed 4stroke diesel that makes 2-3x the HP per displacement is "easier" on the oil?

 

[Captain Ralph]

True but his profile says he’s got a 53 MY, so the reality is he can’t use his 15W40 suggestion without causing engine damage.

In re-reading his post again, What I miss read a couple of times, He is asking about using 15w40 in place of 40w.
You are correct, That is not good for a Detroit.

 

[cww]

Explain this phenomena please. 2strokes have much tougher duty on liners/pistons? A modern high speed 4stroke diesel that makes 2-3x the HP per displacement is "easier" on the oil?

Well, yes. Everybody thinks of Detroits as sloppy engines because they were still doing weird stuff like using cork seals for some things into the 2000’s with inevitable oil leaks to follow. They also get a bad rep because of the sportfish guys in every marina with 15,000 hours but won’t do an overhaul who kill every mosquito in a 2 mile radius when they start them up. When properly maintained they’re wonderful engines. I don’t think the modern stuff will give you the same service life. I just overhauled mine, zero smoke, zero leaks. Their internals have very precise and tight clearances. But to your question. I think the real issue is probably the +/- 90 degree angle between piston rings and those air grates in the side of the liners that detroits use as intake valves that’s tough on oils. The factory did a lot of testing and put out a TSB prohibiting the use of multigrade oils.

 

[jim rosenthal]

The instruction to use particular single-grade oils in 2-cycle DDs has been around since I got into boating, which was in the 1980s. I would imagine that the factory, having more experience with the engines they built, would know better than any other source what oils to run in their engines, and, more importantly, what oils to avoid.

 

[Captain Ralph]

There is a lot of stuff in CF2 oil that is a must for Detroit 2 stroke engines. So no regular 40w oil will do,
Remember to find that API spec with the rating of CF2.

 

[rustybucket]

As others have said: No multi-weight oil in 2 cycle detroits. It is bad news and will lead to cylinder wall scoring pretty quickly.

Napa has been my source since delo 100 40wt has become all but unavailable in my area.

75118 is the CF2, 5 gal from napa, can't beat the price either, it's significantly cheaper than I was paying for delo 100.

Seems like most coastal napas carry a few buckets of this stock, but they can all seem to get whatever you need in a day or two.

I also use NAPA filters for oil, trans and coolant. So it's nice to be able to get everything from one place.

 

[major hattitude]

Thank you was able to find at Napa much apricated !!

 

[brettportzer]

I have been buying Delvac 1240 from Summit since 2019, and it has always been a decent price and free shipping.

They seem to be out of stock right now, which I somewhat anticipated, so I stocked up a little bit this summer and have 40 gallons on hand currently.

 

[krush]

As others have said: No multi-weight oil in 2 cycle detroits. It is bad news and will lead to cylinder wall scoring pretty quickly.

Or it could be that in the old days, detroit rated oil was lower ash?!?

You mean to tell me modern synthetic super slippery oils that basically eliminate all metal wear inside engines is not good enough for 100year old detroits?

 

[jim rosenthal]

It may not be. What's clear to me is that experimenting with boat engines could end up with you needing a very expensive overhaul. Why would you take the risk?

Full disclosure: I have been running a synthetic Mobil in my Cummins marine engines- but that was after a West Coast Cummins shop advised me they had been doing it for years. I would not do it on my own without someone I trusted endorsing it.

Detroit Diesel no longer makes 2 cycle diesels, as far as I know, so my guess is that there isn't any research activity in figuring out which modern oils can safely be used in DDs. If I were running DDs, I'd stick to what most closely matched the specs they originally published. Boat engines give enough trouble and require enough maintenance as is, without deliberately running a non-approved oil.