Rotella T6 5W-40 for YM155D?

NoSmoke · May 17, 2023

Hey, I have a Golf TDI for which I use the Rotella 5-40. Thinking of buying it by the pail and also using it for my YM155D. One reason in particular is that it's a hard, old weather start (I dunno why, the Therostart works and it runs fine once it's going). Anyhow, was wondering if the 5-40 would be advisable for this tractor?

Any advice appreciated...

Yander · May 17, 2023

I see no reason not to, that's what I would be running in it if it was mine.

Yander · May 17, 2023

I would be surprised if it helps you much with your cold start though.

bmaverick · May 17, 2023

NoSmoke said:
Hey, I have a Golf TDI for which I use the Rotella 5-40. Thinking of buying it by the pail and also using it for my YM155D. One reason in particular is that it's a hard, old weather start (I dunno why, the Therostart works and it runs fine once it's going). Anyhow, was wondering if the 5-40 would be advisable for this tractor?

Any advice appreciated...

Not certain really.

The vintage Yanmars of the YM, F, FX, RS, KE, era machines are 5W30 winter and 10W30 summer. This is per the Yanmar and Deere docs.

Here is one of the types that work.

The need to have the oil work in heat and to push the heat out of the engine is a plus. 15W40 keeps heat trapped in the engine longer. Heat buildup will cause heads and gaskets to fail.

ponytug · May 17, 2023

I would not use a 40 weight oil in an engine that was specified for 30 weight oils. Don't be misled by the 5W part into thinking it will be a less viscous oil at temperature. It won't. A 5W40 oil is going to be a 40W oil when it warms up.

40W is significantly more viscous than a 30W oil, this will reduce the efficacy of the lubrication (harder for oil to penetrate into close tolerance/high pressure areas) and the more viscous oil adds work load to the engine. In general, an engine specified for a lower weight oil has tighter tolerances throughout the engine, and will be under lubricated with a heavier weight oil.

All the best,

Peter

runningbird · May 18, 2023

I use Rotella T-6 in my tractors, our Subaru's , dodge trucks with Cummins, and my wife's jeep liberty with a diesel. Lots of info out there on T-6 . However we seldom see temps under 15 degrees, and summers are over 100 degrees.

Any way T-6 was not an option in the 80's so of course it's not listed.
My 70 roadrunner 440+6 calls for sae 30 weight. Of course that's not what I use.

clemsonfor · May 18, 2023

runningbird said:
I use Rotella T-6 in my tractors, our Subaru's , dodge trucks with Cummins, and my wife's jeep liberty with a diesel. Lots of info out there on T-6 . However we seldom see temps under 15 degrees, and summers are over 100 degrees.

Any way T-6 was not an option in the 80's so of course it's not listed.
My 70 roadrunner 440+6 calls for sae 30 weight. Of course that's not what I use.

These are the same reasons why people don't run whale oil and straight 10w, 20w or 30w in old vintage tractors. These multigrade oils didn't exist back in the day if they did you would see them included in original literature because they are superior oils .

As for would a 5w vs a 15w oil start easier, in theory yea and it will spin a bit quicker but I don't think enough to matter unless your down around -20 to +10f probably. As for parasitic HP loss, sure it's a thing but again would you tell in fuel consumption or available power while mowing or pulling a disk I don't think you will ever know.

I would say do what you feel comfortable, I would not say it will hurt. But synthetic oils are pretty good cleaners and you may if you have oil build up or sluge around your seals it's possible the sun or semi syn oil will clean some of that off and cause leaks where you may not have had them before. But none of these oils will hurt it do what you feel comfortable with .

Jtullis13 · Wednesday at 10:03 AM

Reviving this thread. Has anyone had any issues using 5w40 or 15w40 in their tractors? I have seen some posts on TBN that we should only be using 10w30 and not a 40 weight oil due to heat retention. Is this more important in the thermal syphon systems or all Yanmar tractors? I have have been using Rotella T6 5w40 since I got my tractors and haven't had an issue, but I also don't want to have any negative side effects down the road either. I am willing to put 10w30 in them if that is truly the case. I live in Nebraska and the summers it can get over 100 degrees and long stretches of 90+ degree weather.

Open to any suggestions or experience negative or positive, let me know.

careyo63 · Wednesday at 10:09 AM

Used it for Yrs. on the YM2000. First few oil changes 20W-50.

bmaverick · Wednesday at 7:13 PM

Jtullis13 said:
Reviving this thread. Has anyone had any issues using 5w40 or 15w40 in their tractors? I have seen some posts on TBN that we should only be using 10w30 and not a 40 weight oil due to heat retention. Is this more important in the thermal syphon systems or all Yanmar tractors? I have have been using Rotella T6 5w40 since I got my tractors and haven't had an issue, but I also don't want to have any negative side effects down the road either. I am willing to put 10w30 in them if that is truly the case. I live in Nebraska and the summers it can get over 100 degrees and long stretches of 90+ degree weather.

Open to any suggestions or experience negative or positive, let me know.

From old postings in the YTOG archive (GeoCities 1996/Yahoo) up to 2019, using 15W40 has caused over heating retention and heads warping with gaskets blown. More often with the 2-cly engines. It does happen with the 3-cly engines too.

Both Deere and Yanmar point to 10W30 and SAE straight 30W for summer uses. Yanmar vintage machines, key word is vintage, are engineered to JIS specs and not SAE. Thus the oil passages and clearances are much tighter.

I use Rotella T4 10W30. And this year has been the coolest summer I can recall out in the northern mid-west. I would swap to the SAE 30W if it got hotter.

This is the official Yanmar 10W30 oil for our vintage YM, F/FX, KE, RS and other series machines before 2001.

Some of the Yanmar YM domestic manuals do have errors using the wrong oils. I went to the official Japan site to get clarification. This is the reason for the screen captures I posted here from pre-2018.

Likewise, Yanmar manuals also state to use Deere 303 hydraulic oil, yet it's banned in several counties do to it being SPERM WHALE OIL.