I use 10w-30 in my generators. It's the best coverage for my area in N.Ohio. It should work well for your area too during the colder months..
Portable Generators - 15W40 in freezing weather?
- Thread starter SupremePossum
- Start date
If the engine is above freezing when starting ,yeah.
And for how long does this 13 degree temperature last? You might spike down that low at 0730 in the morning but pop back up 30 minutes later. The genset and its oil will have thermal mass to coast through. Remember we had gas engines for sixty years before multigrade oils came out and they were starting in winter back then... by crank or 6 volt electrics!
If you want to worry, what's the RVP on the gasoline in the system? Did you buy it when it was 75 degrees out? It might hesitate to light off when it's super cold.
I think you need to test your system on the coldest morning you can forecast.
If you want to worry, what's the RVP on the gasoline in the system? Did you buy it when it was 75 degrees out? It might hesitate to light off when it's super cold.
I think you need to test your system on the coldest morning you can forecast.
If it specs 5w30 then a 5w40 or 0w40 should be fine.
Or just run 5w40 and "waste" $5 of oil by dumping out the 15w40 instead of wasting hundreds on block heaters and battery packs and all sorts of craziness.
It's just me, but if I'm loaning out my generator, I want it absolutely to work for them. I would just use a 5w30, or 0w40 and not worry.
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4WD
$50 site donor 2025
If that had happened - 17 palm trees would have lived at my place …
Two made it back after a couple years - still not what they were …
Pull starts that don’t start easy anyway - don’t need 15W whatever
4WD
$50 site donor 2025
Yep - I gave away an 8500W with 8 hours so I’d not have to haul it to them or I’d be out of town … Lots of folks cant drop $900 on something like a portable generator …
I left 5W30 in it bcs it’s big for a pull start …
I wouldn't think twice about leaving in the 15w-40. If it's 13* when you have to start it, have them put it in the car for 20 minutes with the heat on, or just store it inside the garage or house where it will be 45* at the coldest. When they need it in the summer you'll be glad they are running it with 15w-40. Or better yet, say to them when the power is on...see that gennie over there?..... you need one of your own.
4WD
$50 site donor 2025
That’s what is overlooked in some comments - he’s got a big whole house on 5W30 that has capacity - portable gens don’t hold but a quart or two …
4WD
$50 site donor 2025
Guess it depends - my 2nd largest and largest portable is 211 lbs - yet is an easy change of 1.5 quarts …
Block heaters are $15 for 2...
IIFC Briggs recommended syn 5/30 for all temperatures, that's what I use in my B&S 5,000 watt unit, I ran it on this oil at least 10 hrs a day for 2 weeks during Superstorm Sandy with basically no oil consumption.
PS (second pic)
make up something like this for a no-mess generator oil change....
PS (second pic)
make up something like this for a no-mess generator oil change....
The only oil issue I know of with thicker oil is in the Honda EU2000 or EU2200. When cold the think oil doesn't flow back fast enough to keep the low oil switch from tripping. Let them idle till the oil warms up if they will run then they are fine.
Finally sat down so I can read these comments fully!
I ordered the 50w block heater pads for $15. It will be interesting to see how they do, honestly I just want to play with them!
Yes, I could possibly change the oil to 5W-30 and save the oil that's in there, but that is an awfully messy idea for a generator that may not even get ran
I could dump the oil, but that's just a waste. Just because I have a large stock of 5W-30 and a big generator doesn't mean it makes sense to throw money down the drain
I got the idea to run 15W-40 from this forum, everyone said in the hot Texas heat with these cheap splash lube engines, you want something thicker like that. So switching back to 5W-30 just puts me where I started
I could switch to 5W-40 permanently, but I thought the general idea was that the 5W oils sheered too easily? I'm no expert, just reading other peoples advice which is why I settled on 15W-40 for then.
If the block heaters work well and stay stuck on there, I feel like it may be a winning idea. 50w of AC power isn't hard to come by!
I ordered the 50w block heater pads for $15. It will be interesting to see how they do, honestly I just want to play with them!
Yes, I could possibly change the oil to 5W-30 and save the oil that's in there, but that is an awfully messy idea for a generator that may not even get ran
I could dump the oil, but that's just a waste. Just because I have a large stock of 5W-30 and a big generator doesn't mean it makes sense to throw money down the drain
I got the idea to run 15W-40 from this forum, everyone said in the hot Texas heat with these cheap splash lube engines, you want something thicker like that. So switching back to 5W-30 just puts me where I started
I could switch to 5W-40 permanently, but I thought the general idea was that the 5W oils sheered too easily? I'm no expert, just reading other peoples advice which is why I settled on 15W-40 for then.
If the block heaters work well and stay stuck on there, I feel like it may be a winning idea. 50w of AC power isn't hard to come by!
I know it’s absolute overkill, but I went with the 5w40 CC CK-4 from HPL for my generator. Any 0/5wXX will be fine, I used to use bRotella 5w40 when I had a snowblower.
With how cheap you can pick up good 0&5w synthetic oils these days, the only justification IMO for a 15w oil is if 1: it’s completely free, and 2: it’s going in something like a 1940s Farmall.
Just doing some head math, if you leave the 50w heat pad plugged in 24/7, and your electric is just $0.10/kWh, you’re talking ~$4/mo, IF the 50W pad is enough to make any meaningful increase in oil temps (you’re going to lose a huge portion to the heat sink that is the engine block). Think about it- the very best ICEs are about 38% efficient, and generator engines are probably in the 25-30% range, meaning for every 5HP of output the engine is wasting about 12HP of heat, or ~9kW for about 3.7kW of output. 50W is likely going to be inconsequential especially if there is any moving air near the cylinder block.
Personally, I think it’s safer, smarter, and potentially cheaper to just go to a year-round friendly winter rating in the appropriate oil grade.
Either way, let us know what you find if you can do some temp gun tests on the cold dipstick and after the pad’s been on for 24 hours. Thanks!
