Generator oil - ideal all-weather fill?

M

mark pruett

Joined
Jan 18, 2003
Messages
320
Location
Dallas, TX
So I was down at my mom's place this past weekend cleaning some stuff out of the shed that my dad had left in there before he passed away, and I found a generator that doesn't seem to have had much use. It's a DuroStar DS4000s, and the manual says that it likes 5w-30 below about 30 degrees, 10w-30 between about -5 and about 90, and straight 30 above about 55. Based on what I know, it's kind of an idiosyncratic set of recommendations- see the picture. What I'm trying to figure out is what the ideal oil for it might be for year-round standby use; here in Dallas we routinely have winter temps in the 20s, and summer temps around 105.

I'm thinking maybe something like a synthetic 10w-30 of some sort, or even the old jug of SN rated Mobil 1 0w-30 that I have out there might work adequately in the event of a power failure. What I don't want to do is seasonal oil changes for a standby generator. Any opinions?

gen_oil_spec.jpg
 
For your climate I would favor either a synthetic 10w-30 meeting ACEA A3/B3 specifications or any 15w-40. ACEA A3/B3 requires a minimum HTHS viscosity of 3.5 and a 15w-40 will be slightly higher.
 
The old jug of Mobil 1 you have is fine. It's a low compression, splash lubed, constant RPM engine. It doesn't need ACEA A3/B3 specs.
 
Any xW-30 would be fine. A similar recommendation table is made for newer lawnmowers that includes full synthetic 5w-30 spanning from -20*f to 100*f.

5w-30 or 0w-30 would make it easier to start below freezing. You may see marginally higher consumption with 10w-30 above 100*f.

Or, if you have a 5w-40 for a Euro car or 15w-40 for a diesel, that wouldn't hurt either for summer use.

Whatever you have will work, I wouldn't run out to the store for something special
 
+3 any nice syn 10w30. I typically use sale/rebate leftovers that don't make a full car engine's worth.
 
Me too. 0W40. I use it in my equipment for year round use. We can get in the single digits in winter and near 100 in summer.
 
Zaedock said:
It doesn't need ACEA A3/B3 specs.
Click to expand...
Well, yeas and no. No, it is not required. Yes, it is a good idea. See below.

SAE-J300-Chart--PNG-_k25s6uy7.png


A 10w-30 could have HTHS as low as 2.9 but a 10w-30 meeting ACEA A3/B3 will have a minimum HTHS of 3.5 which is a good idea IMHO. Also take notice of the footnotes regarding 5w-40 vs. 15w40.
 
Overthinking!!! I put an old jug/leftover oil from your stash in those generator, any usual viscosity.
You probably only need less than a quart anyway.
 
mark pruett said:
Yeah, it's really more the high temps that have me concerned, not the lower ones.
Click to expand...
Which is why you need to focus on HTHS viscosity. This is where the rubber meets the road. To be more precise, it's all about what's going on at the piston rings and crankshaft to connecting rod bearing.

As a matter of full disclosure, I have RT6 5w-40 in both of my generators here in southeastern PA. Temperatures above 100 F are extremely uncommon here. 15w-40 might make more sense in your neck of the woods.
 
I think I'm going to use this:

Amazon.com: Valvoline Premium Blue SAE 10W-30 Diesel Engine Oil 1 GA: Automotive

Amazon.com: Valvoline Premium Blue SAE 10W-30 Diesel Engine Oil 1 GA: Automotive
smile.amazon.com

Basically it's a 10w-30 HDEO rated CK-4 (HTHS >= 3.5) for diesel, SP and SN Plus for gas engines, and is recommended for natural gas engines as well. Since I'm planning on eventually converting it to run on natural gas, that's a bonus.
 
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