Rotella straight 30 Wt oil

[rdodd]

A friend of mine was at wallyworld the other day and said rotella straight wt. 30 oil is still the ci rating. For those people who don,t want to run the new cj rating why not just run the st wt 30 oil?

 

[KOG]

Why, oh why, do people want to run straight grade oils or non detergent oils? You can still buy CI oils, just shop around.

 

[therabbittree]

only reason to run straight weight is for a 2 stroke detroit diesel. .

 

[Greenleaf]

The 30 and 40 is made for the two-stroke. I don't remember why it was. I was in charge of many-many 2-stroke engine at one time.



You can put it in. It's just a bit thick when cold.

 

[Niki]

I've always wondered, what is a 2 stroke diesel and how is it different from a conventional diesel?

 

[Freidhof]

Dad runs 30 wt in everthing diesel from his 93 Dodge to the farm tractors and skid loaders. Swears by it. Argue all you want, but I doubt you will ever get him to change. Seems to work alright I guess.

 

[rdodd]

15/40 oil is just 30 wt oil with extenders in it.

 

[KOG]

No, 15W-40 is 15W with a viscosity index improver added. Unless it's a synthetic in which case it can be compounded to meet both viscosity requirements with no added ingredients.

Oil ratings are trickier than you probably realize.

 

[dpuckett]

The old Ford owners manuals actually recommend running 30wt in the summer in the old (83-89) diesels. Not sure why, but they did. The thing i have noticed on lots of 30wt diesel oil is it is normally 2-3 API ratings behind the 15w40.



I have been able to find CI4 oil, at Wally World, even. Look just down the shelf for the SuperTech. Scored better than Rotella in the oil write up in the TDR magazine a few months ago.



Daniel

 

[B.G. Smith]

I've always wondered, what is a 2 stroke diesel and how is it different from a conventional diesel?

If you don't have your answer, shoot me a pm and I will try to explain what I know about them. bg

 

[jimnance]

If you are in a temperate location like Florida or Southern California there is absolutely nothing wrong with running 30W. In colder climates the lower viscocity of 15W40 is needed to assure prompt lubrication on start up. I'd suggest the multi-grade if starting temps are going to be below 32 f.



If you are going to be running a lot in very hot temperatures (+ 100 f) it might be a good idea to run something heavier like the 15W40.



Otherwise, 30W is a fine oil. Just don't use non-detergent oils. Not good.

 

[TAbbott]

On a 2 stroke diesel, every other stroke is a power stroke. Every time the piston goes down, its a power stroke. On a 4 stroke engine, it's every other down stroke being a power stroke, with the other down stroke being an intake air stroke, filling the cylinder with air to be compressed by the upstroke just prior to the power stroke. 4 strokers can run naturally aspirated - no blower or turbo. 2 strokes need the blower or turbo to scavenge, or fill the cylinder with air when the piston clears the exhaust ports at the bottom of the cylinder liner and the intake valves are open at the same time. Make sense now?

 

[TAbbott]

On edit, I think those are intake air ports at the bottom of the liner, with the exhaust vlaves located in the overhead... .

 

[Greenleaf]

Right. And the reason the 2-stroke will not make twice the power (due to more power stokes) is the fact the combustion chamber is only partially filled with air.



Pertty cool though to look inside the liner at the cyl wall/piston/rings with out taking the engine apart. To do that on a four stoke you'd have to way-over boost the engine... ... ... ... ... ... ... . :-laf



In terms of oil, I'd skip the Rotella and use Scheaffers Semi-synthetic 15-40. Yeah, it costs more, but you change it much less often and I have the oil sample proof that it is far better then Rotella in terms of wear metal found in your used oil.

 

[jimnance]

Just nit-picking here, but a two stroke diesel does not require a blower. Because of the port arrangement and scavenging that needs to take place it would be horribly inefficient and gutless without one. Of course a N/A four stroke diesel won't exactly set the world afire in a drag race.



Because of the incomplete combustion inherant in the two stroke design, they are not very efficient even with a turbo. The old Detoits in our trucks would get 5 MPG on a great day, 4. 5 MPG typical. The same rig powered by a four stroke of the day would get about 6 MPG. At one point I saw numbers close to 7 MPG on modern designs. The series 60 by Detroit was notable for turning in good numbers.



With the emissions systems on more current designs we are closer to 6. 5 MPG.



The old two strokes would probably benefit from the CJ diesel oil since the incomplete combustion tended to load the oil fairly quickly.

 

[therabbittree]

jimnance said "Just nit-picking here, but a two stroke diesel does not require a blower. Because of the port arrangement and scavenging that needs to take place it would be horribly inefficient and gutless without one. Of course a N/A four stroke diesel won't exactly set the world a fire in a drag race. "



Well a two stroke Detroit Diesel DOES need its blower to run . . It won't run without it. A Detroit Diesel without a turbo are still a naturally aspirated engine. etc

 

[Greenleaf]

I don't believe it would start. I don't recall ever seeing one with out one. But I was just a parts changer years ago on the 54/76/92/149 series. I hope them be the correct model numbers.



It wouldn't get a charge of air to compress and fire the air/fuel mix. The 149 has four turbos. When they begin to spool, the wate gate bypasses the blower becasue then it just gets in the way of air flow.

 

[KOG]

Detroit two strokes do require a blower and they are never naturally aspirated as a result. They use turbos to add boost because the turbo is more efficient at adding boost than the mechanical supercharger.

 

[Gary - K7GLD]

If you are in a temperate location like Florida or Southern California there is absolutely nothing wrong with running 30W. In colder climates the lower viscocity of 15W40 is needed to assure prompt lubrication on start up. I'd suggest the multi-grade if starting temps are going to be below 32 f.



If you are going to be running a lot in very hot temperatures (+ 100 f) it might be a good idea to run something heavier like the 15W40.



Otherwise, 30W is a fine oil. Just don't use non-detergent oils. Not good.

YUP - That's the way I understand it as well. Actually, in a constantly moderate climate, a single-weight oil should be just fine, and has lots fewer extenders and similar additives that are there ONLY to provide the ability to maintain viscosity stability at widely varying temperatures - and every ounce of an extender added to an oil REDUCES the actual lube content by the same amount!



And, there is no connection between detergency and whether an oil is straight weight or multi-weight...

 

[JLEONARD]

And, there is no connection between detergency and whether an oil is straight weight or multi-weight...

Yes that's true..... but a straight weight has less additives... therefore it is preferred by "traditionalists".

I all actuality either will work but when the temps get low you need a multiweight... there is a chart that tells at what temp the engine simply will not spin fast enough to start of the oil viscosity is too high. Been there, done that.

Either way, I doubt you will find very many instances if any of an oil weight related failure in our application between 30, 40, and 15-40.



And on the "other topic" I didn't know that a 2 cycle diesel needed to have a blower or turbocharger... and guess what... I don't really care either. It is what it is.

Actually there is one at Mystic seaport that does not have either so there. Of course it's an antique.

Jay