Kubota engine oil recommendation

[Foothill Rancher]

I guess my beef here is that we're all being told something different.

Even though we live in different parts of the country some of our temps are close to the same and the eastern half of Kubota is saying something different than the western half.

JD can use a 0w-40, are Kubota's engines that much looser that we should be using 15w-40 and can't use 5w-40? The oil weight difference doesn't seem that great that it would matter unless their worried about the high temps, but 40w should be the same on either oil.

When I got my tractor it was fine at start up, after the 50hr service the engine rattles for a few minutes after startup, it probably had 10-40 in it from the factory and the dealer did use 15-40.

In my area 15-40 is fine in the summer and I know it's suppose to be good down to 5+ degrees. If I use the 10-40 in winter and 15=40 in summer then I will be changing my oil about every 30 to 35 hrs, I felt that the 5-40 would do away with this is the main reason I was going to use it.

If it didn't make such a loud rattling on startup I really wouldn't say to much about this except for the fact that Kubota is giving everyone different answers.

 

[RWEST]

Boy, those sure do seem to be some hit or miss answers you guys are getting!!

I can't imagine any of the excellent 5w-40's out there causing a problem in your 'bota's. One of the guys who works here has a B7800, and has been running RTS 5-40 in it since 50 hrs, with zero issues. As I, and a bunch of other guys who've switched from 15-40 to 0 or 5-40 have noticed, cold starting is much improved over the 15-40's, while giving up nothing to the 15-40's in hot weather.

 

[tom4018]

My M7040 manual has 15w40 listed right in it even below 32F. Been running Rotella 15W40 in it since the 50 hr service.

 

[wrenchturner]

The additive in oil that makes it multiviscosity also causes the piston rings to stick in the grooves after long term use. More of this additive is needed for 10W40 oil than 15W40 oil. I know it has been recommended to not use a 10W40 oil for this reason. I will bet that if you look at your owners manual it will show to use a straight 30 viscosity oil when temperatures do not fall below about 70 degrees. Synthetic oils are more viscosity stable so I would not be concerned about the piston ring sticking problem. The piston ring sticking problem is not something I have read about lately but I do know it has been a problem.

 

[piller]

This link on the kubota web site:
Kubota Tractor USA - Lubricants Schedule
does not mention 15W-40 anywhere. The link says 10W-30 is good up to 77 degrees F, above that it recommends 10W-40.

My kubota operators manual also says 10W-30 or 10W-40, it does not mention 15W-40.

The person at Kubota headquarters in Atlanta, GA that I spoke with said to use 10W-30.

Yesterday I changed my oil and used Kubota 10W-30.

 

[Lefty_Kubota]

just make sure you use oil that is for diesel engines..
I use the rotella 15w40, cause thats what we put in all the Powerstrokes, Cummins and Caterpillar diesel engines where i work..

 

[wrenchturner]

I just checked my MF1250 owner's manual and it says to use straight 30 oil OR 10W30 oil when the temperatures are above 78 degrees F. It is well documented about the additive used to turn a single viscosity oil into a multi-viscosity oil causing piston rings to stick. I first read about this in Popular Mechanics some 20 years ago. Equipment owners need to be aware of this issue. Of course in the winter you have to run a multigrade oil but why would you run a winter oil in the summer anyway after all what do you think the W in 10W 30 stands for? The synthetic oils probably do not have this problem due those oils being more viscosity stable. I have taken too many engines apart with the rings stuck in the grooves. Read what Bob is the Oil Guy has to say or just google piston ring sticking and multiviscosity oils.

BMCNO Motor Oil 101

 

[DieselPower]

That may be true with older oils and the low end products but today's polymer technology has come a long way. Many are not even the shear prone straight chain molecules anymore. Science has brought us the almost indestructible star polymer. They tend to be 12 point linked molecules that expand and contract with temperature variations instead of the coiling up and straightening out like the older straight chain molecules.

It's been a good many years since I have seen a failure analysis that indicated any type of VII polymer formations on piston rings and lands. The culprit in most failure analysis I see these day's are due to varnish and gum deposits caused by lower quality base stocks and the increased operating temperatures today's engines run. Even this type of long term failure has greatly decreased over the years. In the power generation turbine world varnish problems have greatly decreased over the past 5-10 years due to lubricant improvements.

I would have no problem suggesting a 10W/40 oil to one of my customers. I would however suggest the use of a 15W/40 diesel specific oil. The additive package in a diesel specific oil is much more robust than that of a automotive type oil. Greater anti-wear package and usually a much higher TBN. For cold weather operation I would suggest a 10W/30 diesel specific oil. About the only straight weight diesel engine oil I sell anymore is for 2 stroke Detroit Diesel engines. And since the introduction of API CJ-4 oils many of my 2 stroke DD engine customers are now using multi-viscosity CJ-4 rated oil. Upon scheduled tear downs they are finding the new lower ash CJ-4 oils work fine in the old 2 strokers with no indication of increased deposits.

 

[Foothill Rancher]

That may be true with older oils and the low end products but today's polymer technology has come a long way. Many are not even the shear prone straight chain molecules anymore. Science has brought us the almost indestructible star polymer. They tend to be 12 point linked molecules that expand and contract with temperature variations instead of the coiling up and straightening out like the older straight chain molecules.

It's been a good many years since I have seen a failure analysis that indicated any type of VII polymer formations on piston rings and lands. The culprit in most failure analysis I see these day's are due to varnish and gum deposits caused by lower quality base stocks and the increased operating temperatures today's engines run. Even this type of long term failure has greatly decreased over the years. In the power generation turbine world varnish problems have greatly decreased over the past 5-10 years due to lubricant improvements.

I would have no problem suggesting a 10W/40 oil to one of my customers. I would however suggest the use of a 15W/40 diesel specific oil. The additive package in a diesel specific oil is much more robust than that of a automotive type oil. Greater anti-wear package and usually a much higher TBN. For cold weather operation I would suggest a 10W/30 diesel specific oil. About the only straight weight diesel engine oil I sell anymore is for 2 stroke Detroit Diesel engines. And since the introduction of API CJ-4 oils many of my 2 stroke DD engine customers are now using multi-viscosity CJ-4 rated oil. Upon scheduled tear downs they are finding the new lower ash CJ-4 oils work fine in the old 2 strokers with no indication of increased deposits.

Are the new CJ-4 oils using the new star polymers?

 

[DieselPower]

Many are, usually higher quality products. The problem with using multi-viscosity oils in DD engines isn't the polymers but the increased ash content. CJ-4 oils have a much lower ash content than any previous 4 stroke API rated oil and are getting close to the ash limit of 2 stroke oils. The ash limit was greatly reduced because these oils are designed to be used in modern diesel engines with particulate filters. The previous 4 cycle engine oils had a higher ash content (non combustible elements) that can plug up a particulate filter.