Oil change for diesel lawn tractor

   / Oil change for diesel lawn tractor #1  

mtoneill

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Aug 19, 2009
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I have a 25-year-old Simplicity 7790 diesel lawn tractor. Here's what the manual says about oil: "Use oils of the CD (DS series 3) service classification." And that the viscosity for summer should be SAE 20W. Could anyone recommend an oil that would work for this situation?

Thanks.

mto
 
   / Oil change for diesel lawn tractor #2  
Obviously, oils and their service classifications have changed a wee bit in a quarter century!! Wow, that's a really neat thing that the old girl is still going.

At Wally World, you'll find diesel rated oils that will work just fine and are very affordable. You might consider a typical 15w-40, but for the summer, it might be fine. Chevron, Shell Rotella, or WalMart's own house brand SuperTech.

I might be tempted to use 10w-30 in Rotella. It is semi-synthetic and about the right weight to match up to 20W. I don't think it's going to balk at either 10w-30 or 15w-40. For sure, any oil you choose is going to be far superior in technology than oils of 25 years ago.
 
   / Oil change for diesel lawn tractor
  • Thread Starter
#3  
Thanks BP.

We call it "The Beast." It's been very dependable for us. It works great with the snowblower attached. We bought it about 8 years ago and never have had a problem. I've changed oil in it before, but I'm not sure what I used. So that's why I posted on here.

Happy Easter.

mto
 
   / Oil change for diesel lawn tractor #4  
A beast it must be, indeed!! Wonder who made that engine? Mitsu? maybe?

I sure wouldn't run that common 15w-40 in the winter, though. That's a bit much for cold morning starts when you need to plow/snow blow.

Hard to beat a good 10w-30 Rotella for year round use. Silver jug, I believe. But again, the WalMart's own Super Tech (Warren Oil) would also far exceed any spec envisioned by the builders of that engine.
 
   / Oil change for diesel lawn tractor #5  
Rumor has it that Rotella 10-30 has 1 or 2 cc of Chuck Norris' DNA in every quart. The stuff is amazing. :thumbsup:
 
   / Oil change for diesel lawn tractor #6  
I'd use the JD 0w40 synthetic.

I use the Mobil 1 0w30 in my 4010 but plan to switch to the JD one next change. Mobil 1 does make a 5w40 that is more heavy duty diesel rated, but I prefer having the 0w40 for better winter startups.

I switched my very old Gravely 12hp that I had before the JD to synthetic. By the 3rd oil change, it was using hardly any oil. Before, it used on dino and the first two synthetic changes. ALL my engines are on synthetic now, just to reduce my time needed to do oil changes (once/year).

Ralph
 
   / Oil change for diesel lawn tractor #7  
I use Shell Rotella-T 5W-40 synthetic all year in everything. I think you get 10 cc of DNA per gallon.
Good one!! :D :thumbsup:
 
   / Oil change for diesel lawn tractor
  • Thread Starter
#8  
A beast it must be, indeed!! Wonder who made that engine? Mitsu? maybe?

It's a 19 hp Lombardini. I had some 5W-30 Rotella in my garage. I must have been on the right track!
 
   / Oil change for diesel lawn tractor #9  
Are you sure it says 20W oil. I have an 84 7790 with the Lombardini diesel and my manual says (above 68 deg) use 40W oil....and I cant find it anywhere. Am trying to find out if multi-viscosity oils are OK. Haven't heard from Lombardini yet but will let you know if/when I do....Nick
 
   / Oil change for diesel lawn tractor #10  
Both JD and VW allow 0w-5w30 oils in their diesels.

In my old Gravely, I switched it to synthetic. After about the 3rd change, it actually quit using oil. In it, I used the Mobil 1 15w50.

If you use your diesel for snow blowing plus summer stuff, I'd use the Mobil 1 0w30 like I use in my JD 4010. The local JD dealer doesn't seem to carry the 0w40; so, I'll probably stick with the 0w30 or maybe go to the 0w or 5w30 Mobil 1 ESP that I'll need for my VW TDI.

Any modern 0w-5w or even 15w30 oil would be better than a straight 20w oil.

Ralph
 
 
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