What weight Oil does a given manufacturer make and why

[Silvic]

I want to thank those who answered and there were some good comments. Having multiple highfalutin technical/engineering degrees but none in engine lubrication or chemical engineering I am always willing to learn something new.
But I can say categorically the often quoted if you can use 15w40 then you can use 5w40 is not always true. My manual states otherwise. Talked to the company experts and they say it is not a misprint thus I have to believe them. I want to keep my enigines in warratee (if they are still in it) thus I will go with manufacturer specs.

As one person posted it is about demographics. They produce what sells. I have two diesel engines that will take 5w-40 as primary oil, one that will take it but it is not the listed preferred viscosity and one that clearly forbids it. I was merely questioning why there seemed to be no synthetics in some weights.

There is a lot more to be concerned about than viscosity . Most people here appear unaware of API ratings which are vital. For example the wrong motor oil , a high ash four stroke diesel oil will ruin a two stroke Detroit. Some low ash post 2007 diesel oil will cause extra cam/follower wear.

Absolutely true and with the newer engines they are very specific in stating that API specs xxx (the older ones) are not authorized. My newest engine is also very specific in which viscosity not to use as well as the allowed viscosity.

What application is there where 15w40 would work and 5w40 would not? I can't think of one.
From what I understand they both are basically identical at operating temperatures but the 5w flows better when cold for easier startups.

Perkins seems to think otherwise

...snip... As mentioned, the 5w-40 covers everything between. The second number is the working temperature rating, and the first the cold flow rating. If you can use either, the 5w-40 is a better year round oil. After I get through my stock of dino 15w-40 I'm switching to 5w-40 synthetic--tired of molasses in January and punishing start-ups when the block heaters haven't had been running. Supposedly for heavy loading the dino 15w-40 is a "tougher" product and won't shear as much when stressed... don't know if synthetic mixtures work the same or not, but improved stability is one of their selling points.

ditto.. I'm trying to think where 15w40 is ok but 5w40 is not??

My Tier 4 Perkins engine specifically states not to use 5W-40 It lists, believe it or not, 8 different allowed viscosities (some I have never heard of) but specifically states no 5w-40 for some reason)
So not in all cases.


Thanks for the input guys I guess demographics and sales are the answers to the question asked.

 

[Copperhead]

Well, the manuals are not all up to speed with what is going on in the real world. There is not an application that uses a 15w40 that cannot use a 5w40. It is correct, the number before the "w" has nothing to do with viscosity, it is the cold flow rating. The number after the "w" is the viscosity rating. And whether it be a 5w40, a 10w40, or a 15w40, they all have a viscosity of roughly 14.5 - 15 cSt at 100c, give or take a few tenths. And any of these, if they meet the CJ-4 classification, will more than aptly meet the tier 4 standards of any diesel from a little one in a compact tractor or UTV all the way up to a 15L in a commercial truck.

 

[Soundguy]

There is a lot more to be concerned about than viscosity . Most people here appear unaware of API ratings which are vital. For example the wrong motor oil , a high ash four stroke diesel oil will ruin a two stroke Detroit. Some low ash post 2007 diesel oil will cause extra cam/follower wear.

I don't assume people here are unaware of API ratings. just quoting 2-3 lines of info per oil post to say what oil you have gets wordy. especially if your oil carries both C and S ratings.

Hopefully they are mindfull of them anyway.

 

[Soundguy]

My Tier 4 Perkins engine specifically states not to use 5W-40 .

Hmm.. I'd say that says more ( negatively ) about perkins, than it does about the oil ..

I just walked out and grabbed my jug of valvoline premium blue extreme HD full syn 5w40, and the bottle is overflowing with manufacturer specs it meets and exceeds, including the exclusinve cummins 5k mile extended drain warranty.

cat, renault, vovlo, gm, ford, chevy, detroit, navistar... just about every engine maker that makes a diesel is listed. EXCEPT perkins.

That right there tells me something. about perkins.

 

[clemsonfor]

I have been using regular old diesel rated oil in my diesels since forever. I am an the edge of switching to synthetic in a couple of them.

The thing I have run up against is this:
manufacturer A only makes 10w-30
manufacturer B only makes 5w-40
and so on.
For gas engines and diesel as well for the non synthetics there is a large choice of weights for any given brand but it seems you are very limited in the synthetics to one or maybe two brands/manufacturers if you go that route. It seems that 15w-40 synthetic is not really available but 5w-40 is the standard. My manual while allowing 5w-40 restricts it to a range that is not really compatible with my operation. I would like to use one brand but that just seems not to be possible.

Anyone know the background on why synthetics are so limited in the weights that any brand has. Basically each brand has one and only one weight synthetic (diesel rated oil)

5w-40 will work in any temperature that you would want to use 15w40 in and do it better. It will flow better cold and thats all that first number means. There both 40 weight oils period.

 

[clemsonfor]

What application is there where 15w40 would work and 5w40 would not? I can't think of one.

From what I understand they both are basically identical at operating temperatures but the 5w flows better when cold for easier startups.

yep! that is correct

 

[RalphVa]

I agree with copperhead and clemsonfor. You manuals are wrong, but if you're still under warranty you have to follow the manuals, however stupid they are.

Ralph

 

[Copperhead]

And I do! My manual for my JD 825i says anything from 5w30 thru 10w40 for all kinds of ambient temp ranges. I only concern myself with the thing they state afterwards.. must meet API SL or higher. Well the oil I use meets SN, and is a 5w30 synthetic. I rest easy at that point and don't get all wound up in details. I follow the same general principle for all my engines. My Detroit Diesel says anything from 5w30 to 15w40 and must meet CI-4+. I use a 10w30 that is CJ-4 and sleep well at night.

 

[GManBart]

I agree with copperhead and clemsonfor. You manuals are wrong, but if you're still under warranty you have to follow the manuals, however stupid they are.

Ralph

How likely is it that the manuals are wrong, and the company reps told the OP that it's not a misprint? That seems pretty far-fetched.

If they had omitted listing 5w40 it would be one thing, but to specifically forbid it seems very deliberate, not a mistake.

I certainly can't imagine why 5w40 would be a problem when 15w40 is specified, but I'm definitely not a lubrication engineer.

 

[brown40]

It's certainly odd-- the weight , viscosity and profile are supposed to be the common language for lubricant use. Maybe a statistically significant trend popped up with a certain mass produced 5w-40? Reacted with a part, pump, channel, gasket or seal Perkins used. If you checked and double checked, you know what to do to stay in good graces.