# What type of oil for my generator?



## mldollins

I had always heard to use sae-30. I decided to buy synthetic. I looked in the manual and they give sae30 as an option...but also 5w30 and 10w30. They warn that using sae30 with temps below 40 F could cause damage .....huh.....\

They are just not real clear.


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## Darren

I'm interested in what others have to say. I've heard to not use synthetic until an engine is broken in and the rings seated. But what about engines that are filled with synthetic from the factory?


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## arabian knight

mldollins said:


> I had always heard to use sae-30. I decided to buy synthetic. I looked in the manual and they give sae30 as an option...but also 5w30 and 10w30. They warn that using sae30 with temps below 40 F could cause damage .....huh.....\
> 
> They are just not real clear.


 Yes you don't wan tot un a straight 30 in colder temps. 30 wt. gets thicker at colder temps and may not provide that early protection for things before the oil gets warmed up.


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## VaFarmer

weather to use a multy grade oil is a must if running motor in cold temps. flows at a 5w or 10weight depending what you use when cold. Lubes at a 30w performance when warms up, if you use a straight 30w & start engine at around 30 deg or less oil may not flow & you'll blow the engine. I suggest running the 10-30 (if 10w is OK for your temps) so you have the range of oil performace. Still recommend breakin with conventional oil before changing to synthic. Most engines come with a standard oil in them from the factory, run that then change to synthic. I've run Amsoil since the late 70's in numrois vehicles and run all my vans on it. No sludge in the engines and better wear from parts like cam chains. Then you get into the trans oils & differentials with reduced friction.


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## Guest

I use fully synthetic in everything except 2 strokes .


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## rambler

A 90 weight oil is real thick, used for gear cases and such.

A 50 weight oil is kinda thick, some folks will use it in an old, old, worn out engine that is sloppy loose.

A 30 weight oil is what most engines like to run on when they are hot. But that oil can be a tad thick when they are below freezing temps.

A 10 weight oil is good for starting an engine, but for most would get way too thin to run on once the engine heats up.

Newer engines might be built with much tigher tolerances, very small gaps, and they like the real thin small molecules of a 5 weight oil to start up. But again, once everything gets real hot, that is too thin to lubricate well.

So many manufaturers recommend a multi-weight oil. 10-30 acts like a 10 weight thin oil when it is cold, but thickens up a tad when it heats up & lubricates your engine like a 30 weight when it's hot.

Same with a 5-30.

A lot of diesel engines like 15-40 weight oil, and to be honest many farmers only stock that & put it in all their gas & diesel engines.

Be careful of the very new engines tho - a straight 30 or a 15-40 might be too thick for the very tight tolerances some have. Some only want a 0-20 any more!

But anyhow, they are telling you your engine will run great on a 10-30 oil nearly anywhere. You can use a 5-30 especilly if you are in, say, Minnesota in winter & it is bitter cold. And in the summer time your engine will run fine on a straight 30 oil.

They are just giving you some options, which is nice. When in doubt, pick the middle one - the 10-30 in your case. Will work all year around wherever you are.

--->Paul


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## foxtrapper

Engineer and mechanic here. 

Lets start with straight motor oils here. We'll take 30 weight oil. Good strong oil. Works great in the summer and on a hot running engine (which most air cooled engines are). This is why it's the recommended oil for lawnmowers and such. Doesn't break down when hot, great lubrication. 

But, it flows like tar when its cold. Cold like a January morning. In fact, many times the oil pump can't suck it up, and the engine runs without oil for a while until it warms up the oil, and that ain't good! Many an engine has been damaged from this back in the day.

So engineers came up with the multi-viscosity stuff, like 10w-30. It's still 30 oil, but when its cold outside (like winter time, hence the "w"), it flows like a 10 oil. Magic! So on that cold January morning, it flows like pancake syrup, not tar. The oil pump can move it through the engine, and it doesn't starve for lubrication when started up.

Ah, but there is a downside to 10w-30 oil, it's not as "tough" as straight 30. It will break up molecularly more easily than the straight 30. So in really hot and harsh applications, like a lawnmower in the summer, it's not as good. It's generally "good enough", but not quite as good.

You go up and down this viscosity index depending on various things, like weather conditions, application, etc. A lawnmower in Florida runs a whole lot hotter than a car up in Alaska. So you'll need to adjust viscosity accordingly. Looking at start-up conditions, as well as running conditions.

Lots of people confuse gear oil and motor oil viscosity. An easy mistake to make. 90 gear oil, that must be some thick stuff, right? Nope. It's on par with 40 motor oil. They are two completely different indexes. It does not help that numerically it looks like they progress from one to the other. 

So your generator, can it run on 10w-30? Most likely. Almost anything can. But, if it's a hot running air cooled engine, and you use it in the summer, a straight 30 oil would be better. If it's going to be used in the winter, you'll want a 10w-30 oil instead.

Do I apply this to my own stuff? Sure. My snowblower has 10w-30 in it, so I can start it up in the winter. My lawnmower has straight 30. It doesn't get started in the winter, and runs hard and hot in the summer.


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## SmokeEater2

Same here. 10w30 in the winter and straight 30 weight in the summer.


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## Old Vet

I have a large generator (20 KW) and it came with synthetics with it and the manual called for it. Both winter and summer.


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## trkarl

A lot of good oil info here.

http://www.bobistheoilguy.com/cms/


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## Rick

mldollins said:


> I had always heard to use sae-30. I decided to buy synthetic. I looked in the manual and they give sae30 as an option...but also 5w30 and 10w30. They warn that using sae30 with temps below 40 F could cause damage .....huh.....\
> 
> They are just not real clear.


Thanks for starting this diccussion.


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