15W-40 Oil in a generator?

Joined
Sep 1, 2021
Messages
8
I have a generator that is liquid cooled and is run by a small 4 cylinder engine. It runs off of natural gas. I'm looking to change the oil and the recommended oil is 15W40. I'd like to switch over to a synthetic oil. Any 15W40 I find is labeled as being for a diesel engine. Not sure what forum to post this in but figured this one with the hope that the best understanding of synthetic 15W-40 would be here. I'm wondering what you would do.

1. I can just go ahead and use the 15W40 synthetic that is labeled for diesel engines.

2. I could go with a 10W40 synthetic (plenty of brands with a synthetic option in that weight).

3. I could just continue to use 15W40 conventional oil.

I've always understood that oil thickens up with temp and that the synthetic oil does this quicker/better than conventional oil. So I'm thinking 10W40 in synthetic should be no problem. However, I'm inclined to stick with the manufacturer recommendation but I'm not sure if the "diesel" designation actually means anything.

FWIW, the generator has an engine warmer so it will never be super cold even in the winter. Though I do live in Michigan and it's not uncommon to have a very cold stretch in winter.
 
Joined
Aug 20, 2003
Messages
16,678
Location
NE,Ohio
I have a generator that is liquid cooled and is run by a small 4 cylinder engine. It runs off of natural gas. I'm looking to change the oil and the recommended oil is 15W40. I'd like to switch over to a synthetic oil. Any 15W40 I find is labeled as being for a diesel engine. Not sure what forum to post this in but figured this one with the hope that the best understanding of synthetic 15W-40 would be here. I'm wondering what you would do.

1. I can just go ahead and use the 15W40 synthetic that is labeled for diesel engines.

2. I could go with a 10W40 synthetic (plenty of brands with a synthetic option in that weight).

3. I could just continue to use 15W40 conventional oil.

I've always understood that oil thickens up with temp and that the synthetic oil does this quicker/better than conventional oil. So I'm thinking 10W40 in synthetic should be no problem. However, I'm inclined to stick with the manufacturer recommendation but I'm not sure if the "diesel" designation actually means anything.

FWIW, the generator has an engine warmer so it will never be super cold even in the winter. Though I do live in Michigan and it's not uncommon to have a very cold stretch in winter.
a 5w40 syn would be fine.
Viscosity and Viscosity index are important to how much an oil thins out as it heats up.
nothing to do with conventional or syn.

Oil doesnt thicken with temp.. thats why cold oil in winter is like honey and hot oil is closer to water.
 
Joined
Jun 2, 2014
Messages
5,401
Location
Ca.
I'd run 0W-40 in it like all my other generators, Diesel, gasoline or natural gas, air cooled, water cooled.

Especially in Michigan where it can get super cold.

The 0 winter grade will just be easier on everything to turn over and start when its cold.
 
Joined
Dec 19, 2019
Messages
2,947
Location
Muncie, Indiana
What's anyone's experience here with using diesel oil in natural gas engines, I thought you weren't supposed to do that because diesel oil creates more ash than natural gas specific oil and that ash can leave some real nasty deposits on the exhaust valve and ultimately burn the valve.
 
Joined
Jul 12, 2012
Messages
3,792
Location
Caldwell Idaho
What is interesting is I have 2 wheel lines to water the about 4 acres of "field " The engines that move the lines are Honda lawn mower type engines. When the starting temps are 70* f or above the are easy to pull and seem to start the second the pull start rope is moved . I moved them yesterday and the Temperature was 48* and was surprisingly harder to pull and took two pulls to start. I have moved the lines at below freezing temps to move the lines to the center of the field and the engines were really hard to pull to start and took many pulls . This was with 5W-40 Rotella T6. That is oil I have left over from the tractor oil changed. The oil change will be M1 0w-40 Euro oil The lines usually move about 60 feet per move so the oil never really gets past warm. Here is a link with pictures of a wheel line if interested.
 

Timbo750

Thread starter
Joined
Sep 1, 2021
Messages
8
What's anyone's experience here with using diesel oil in natural gas engines, I thought you weren't supposed to do that because diesel oil creates more ash than natural gas specific oil and that ash can leave some real nasty deposits on the exhaust valve and ultimately burn the valve.
This is the type of thing that is my concern. It leads me to option 2. - Just get Mobil 1 in the 10W40 and call it a day.
 
Joined
Dec 14, 2015
Messages
136
Location
Kansas
I have a generator that is liquid cooled and is run by a small 4 cylinder engine. It runs off of natural gas. I'm looking to change the oil and the recommended oil is 15W40. I'd like to switch over to a synthetic oil. Any 15W40 I find is labeled as being for a diesel engine. Not sure what forum to post this in but figured this one with the hope that the best understanding of synthetic 15W-40 would be here. I'm wondering what you would do.

1. I can just go ahead and use the 15W40 synthetic that is labeled for diesel engines.

2. I could go with a 10W40 synthetic (plenty of brands with a synthetic option in that weight).

3. I could just continue to use 15W40 conventional oil.

I've always understood that oil thickens up with temp and that the synthetic oil does this quicker/better than conventional oil. So I'm thinking 10W40 in synthetic should be no problem. However, I'm inclined to stick with the manufacturer recommendation but I'm not sure if the "diesel" designation actually means anything.

FWIW, the generator has an engine warmer so it will never be super cold even in the winter. Though I do live in Michigan and it's not uncommon to have a very cold stretch in winter.
Liquid cooled engine = consistent operating temp say 180-210 degrees
Block heater = easy sub 0 starts
Natural gas = No problems with fuel storage, stale fuel, etc.
15w40 dino oil = Best value lowest cost for your application. Estimate 9.99 to 18.99 per gallon.
--W40 Syn oil = Good choice for Air cooled engine IE: Easy to pull start in cold weather. Still a good option for liquid cooled engine however you have a block heater so Syn not an absolute must have. Estimate 18.99-? per gallon.

Use what you want. Try Syn oil and let us know what you experience. Your engine won't really care if it has Dino or Syn, just be sure to check the oil level often.
 
Joined
Aug 20, 2003
Messages
16,678
Location
NE,Ohio
Liquid cooled engine = consistent operating temp say 180-210 degrees
Block heater = easy sub 0 starts
Natural gas = No problems with fuel storage, stale fuel, etc.
15w40 dino oil = Best value lowest cost for your application. Estimate 9.99 to 18.99 per gallon.
--W40 Syn oil = Good choice for Air cooled engine IE: Easy to pull start in cold weather. Still a good option for liquid cooled engine however you have a block heater so Syn not an absolute must have. Estimate 18.99-? per gallon.

Use what you want. Try Syn oil and let us know what you experience. Your engine won't really care if it has Dino or Syn, just be sure to check the oil level often.
Did you perhaps miss the part where it might need to be started in Michigan winter?

That takes 15w40 off the table.
In Florida sure.
 
Joined
Feb 25, 2019
Messages
818
Location
Texas
Go ahead and use a synthetic 15w-40. T6 with less anti wear additives is still known to reduce wear than higher wear additive t4 so if you use that gen a lot like 50 hours a year or more use t6 or delvac extreme which seems better but both are great. Less than 50 hours a yeah eh cheaper conventional diesel every 25ish hours is fine.

If it only runs like 10 hours a year then it really won't matter what you put in as something else will fail or age to death. Reducing wear is more important in cheaper chinese engines as the machining is good but the metallurgy isn't and chinese engine metals are known to wear faster. Japanese engines don't wear as much. I use t4 since it can go 2 years without running. It's seldom used so I'm not too crazy about the oil. Ill probably switch to cheaper super tech diesel because who cares.
 

Timbo750

Thread starter
Joined
Sep 1, 2021
Messages
8
Thanks for the input. I ended up getting this:


It‘s Wolfs Head 15W40 synthetic blend. I think next year (change oil every year if I have an outage that goes more than a day) I’ll see if I can find that Valvoline that Mark shared. I like that they advertise it for natural gas engines. They didn’t have it where I went (small auto parts store). I owed the guy a favor so I wanted to do some business there. He was really helpful when my generator broke down helping me find a starter. Saved me a couple hundred bucks. He did have the other things I needed (filter, anti-freeze, spark plugs . . .). Tune up time..
 
Joined
Jan 1, 2003
Messages
1,326
Location
Daytona Beach
I've always understood that oil thickens up with temp and that the synthetic oil does this quicker/better than conventional oil. So I'm thinking 10W40 in synthetic should be no problem. However, I'm inclined to stick with the manufacturer recommendation but I'm not sure if the "diesel" designation actually means anything.
This is incorrect thinking. All oil thins out as it gets hotter. AND all oil thickens as it gets colder. It's the DEGREE of thinning and thickening that we need to deal with.
Spend some more time on this forum if you wish to learn more.
 
Joined
Aug 20, 2003
Messages
16,678
Location
NE,Ohio
The OP says it has an engine warmer, i.e block heater, shouldn't be a problem in cold winters.
Missed that,
never heard of a generator with a block heater.
. Seems like it would waste a ton of electricity.. to run a block heater 24/7
and of course if the power is out you cant wait for it to heat up and you have no electricity to power an "engine warmer"
 
Joined
Jul 12, 2012
Messages
3,792
Location
Caldwell Idaho
Missed that,
never heard of a generator with a block heater.
. Seems like it would waste a ton of electricity.. to run a block heater 24/7
and of course if the power is out you cant wait for it to heat up and you have no electricity to power an "engine warmer"
If the power goes off the oil will be warm. I am sure the heater is thermostatically controlled so it won't run during the warm times and T\the heating costs are part of the costs of " doing business."
 
Joined
Oct 30, 2006
Messages
13
Location
Cape Cod Ma.
I have a generator that is liquid cooled and is run by a small 4 cylinder engine. It runs off of natural gas. I'm looking to change the oil and the recommended oil is 15W40. I'd like to switch over to a synthetic oil. Any 15W40 I find is labeled as being for a diesel engine. Not sure what forum to post this in but figured this one with the hope that the best understanding of synthetic 15W-40 would be here. I'm wondering what you would do.

1. I can just go ahead and use the 15W40 synthetic that is labeled for diesel engines.

2. I could go with a 10W40 synthetic (plenty of brands with a synthetic option in that weight).

3. I could just continue to use 15W40 conventional oil.

I've always understood that oil thickens up with temp and that the synthetic oil does this quicker/better than conventional oil. So I'm thinking 10W40 in synthetic should be no problem. However, I'm inclined to stick with the manufacturer recommendation but I'm not sure if the "diesel" designation actually means anything.

FWIW, the generator has an engine warmer so it will never be super cold even in the winter. Though I do live in Michigan and it's not uncommon to have a very cold stretch in winter.
Is it a two or four pole generator? Two pole generators run at 3600 rpm vs four pole at 1800 rpm?
Something to consider, then follow manufacturers recommendation.
 
Top