# winter oil



## film495 (Nov 1, 2013)

I have an old K301S in a garden tractor. It says use 10W30 for winter use and 30W for weather over freezing. My question is, if it is 10 degrees outside, and if it is an air cooled engine, will the engine then not run cooler then if it is say 90 degrees outside? I used 5W20 a couple winters with it and didn't seem to have any issues, but curious if anyone else has ideas theories about this. I'd like to treat the motor well since it seems to be running strong and doesn't burn oil.


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## skunkhome (Nov 30, 2008)

I just use what the manufacturer call for. I have an old K series also and I run 30 HD in it year round as we rarely have weather below 40°. I don't have much call to run my tractors when it's cold on my property. If I were to run them below 40° I would use the 10w30. And I do think they run considerably hotter in 90° temps than they do at 10°. I think though that the point of the multigrade is that it flows better and gets to the bearings better before the engine warms up. I have found that my old cast iron L heads use more oil if I use 10w30 in the summer.


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## jhngardner367 (Apr 5, 2011)

Oil does more than just lubricate.
It also helps cool the internal parts. Too light a lubricant,especially during hot weather and it can't shed heat,very well.
A thicker oil,in the hot weather lubes,and cools.
Thinner oils in hot weather,also makes fuel consumption more,since the extra heat causes vaporization in the carb,and manifold.
As Skunkhome said,...Use what is recommended. It'safer.


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## skunkhome (Nov 30, 2008)

jhngardner367 said:


> Oil does more than just lubricate.
> It also helps cool the internal parts. Too light a lubricant,especially during hot weather and it can't shed heat,very well.
> A thicker oil,in the hot weather lubes,and cools.
> ...


 The old cast iron L heads run a lot hotter than modern engines. That extra heat made them impossible, according to the manufacturers, to meet the EPA standards. Almost all your newer engines call for running multigrade oils year round but you can't treat these older engines the same way. I also use non synthetic oils as the design of the engines can't take advantage of the synthetic benefits.


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## film495 (Nov 1, 2013)

strangely enough, the old tractor manual I found, says use 10w30 year round, the manual I found for the snow blower says to use 5w20, and the manual for the motor, says to use 30W when above freezing ... then 5w20 below OF and 10w30 between 0F and and 30F. 

So, what I've been doing is running 30W when above freezing, and then switching to 5w20 synthetic into the winter for snow blowing. Sometimes, it is -10 outside and I have to clear snow, but sometimes it is warmer, maybe 25 degrees. 

I can't really change the oil back and forth all winter based on temperature. I need to be able to start when it is 20 below freezing outside, so I run the lighter weight based on the coldest it might be, but that is not the right weight if it is a little warmer out. Probably isn't a perfect answer.

I ask also because these manuals were written in the mid 70s, so things have changed a little since then. Also, with an air cooled engine, the running temp would have to be very different at say 15 degrees outside vs. 100 degrees F, but that seems like a huge range to use the same 30 weight oil, be that 30W or 10W30, the running temp viscosity is 30 weight, but the actual viscosity must vary greatly as the running temp of the engine must be different. 

I guess the question is academic, for the most part the winter weather is 0-30, but on occasion is below 0. Should I run the oil weight recommended for the most common temp, or the coldest temp we're likely to see?


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## skunkhome (Nov 30, 2008)

I would use the oil with the broadest range as long as it is recommended by the engine manufacturer. In the chart above that would be 5w-30 or 5w-20.


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## film495 (Nov 1, 2013)

it is so weird they through in a 10w40 into that chart. so basically you could be running a 20w or a 40w oil at the same temp, so weird. maybe there are very broad tolerances. It makes me wonder if oil is so much better today than 40 years ago when the manuals were written, that it really doesn't matter.


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## skunkhome (Nov 30, 2008)

film495 said:


> it is so weird they through in a 10w40 into that chart. so basically you could be running a 20w or a 40w oil at the same temp, so weird. maybe there are very broad tolerances. It makes me wonder if oil is so much better today than 40 years ago when the manuals were written, that it really doesn't matter.


I don't know about better but they are certainly different. I would dare say that all the motor oils used 40 years ago are now obsolete. Even the API service classes (SF & SG) referenced in the chart above are now obsolete and should not be used in an engine manufactured today.


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## film495 (Nov 1, 2013)

skunkhome said:


> The old cast iron L heads run a lot hotter than modern engines. That extra heat made them impossible, according to the manufacturers, to meet the EPA standards. Almost all your newer engines call for running multigrade oils year round but you can't treat these older engines the same way. I also use non synthetic oils as the design of the engines can't take advantage of the synthetic benefits.


They recommend synthetic in my VW because the turbo generates a lot of heat, and the synthetic is supposedly more heat resistant. So, if this old engine generates a lot of heat and runs hotter than a modern engine, would the synthetic then be some advantage to regular oil, especially if using a multi-viscosity oil for colder weather? Less combustion chamber deposits and what not? 

I use traditional 30W in the summer, not sure why - it is just what they designed the machine to run on, and not even sure if a synthetic 30W is available.


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## Leb1 (Aug 7, 2015)

Today's oils are looking that years ahead of the SF and SG oils. The 10w-30 oils today don't break down or create deposits like the older oils. So you could safely use a 10w-30 oil year round. For extra protection, you may want to use 10w 30 oil made for diesels as they also meet standards for gasoline engines and are made to withstand the heat created by a turbo . In other words, an EXTRA MARGIN OF PROTECTION.


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## skunkhome (Nov 30, 2008)

The old cast iron L heads produce more products of combustion and have no filter so you aren't going to be able to run the oil extended periods you should be able to enjoy with synthetics. You can run 10w-30 in your older engines but watch oil consumption closely in summer temps. If you start using oil as my old Briggs and kohlers did then switch to 30w. My newer aluminum block engines use 10w30 year round.


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## film495 (Nov 1, 2013)

Is there an advantage to using the Kohler oil or something for small engines vs. using autommotive oil?


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## skunkhome (Nov 30, 2008)

IMO, Yes, there is an advantage to Kohler. If the oil you select matches the API specs listed in your engines requirements there should be no advantage to you in spending the extra money for a premium cost oil. If you don't have to pay a premium, go for it. 

I do have one engine that I can't go into Wally World and find oil for. That is a Mercedes 3L v6 turbodiesel. Though there are quite a few companies that make MB 229.51 approved oil, I have not been able to find anywhere but at Dealers that sell products with that engine or on line. It makes me nervous not to have at least 15 quart supply. The online price is better than what I could find locally even if it were available at NAPA, AutoZone, or my local discount automotive stores.


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## film495 (Nov 1, 2013)

thanks for the input everyone. I don't think it will make too much of a difference what oil I run in the long run, it just becomes one of those things where I ask myself, why am I doing what I'm doing, and since the machine is older want to make sure I'm not going to ruin it by missing something.

oh, I found an article in science journal or something like that, and they tested multi vs. straight weight oils for cooling ability and thermal transfer, and the single weights were far superior for cooling to multi weight oils. so, basically that is the main reason in my opinion why most smaller air cooled engines call for straight 30W in warm weather. so, if you really crank on your engine when it is hot outside, which I really don't, there is a cooling advantage, they sited as much as 4 to 1 for 30W vs. 10W30 in the same brand. I do not think they cited any specific brands though, they were just showing the difference in the types of oils. That seems like a big enough difference to think 10W30 might not be appropriate for warm/hot weather, even though modern oils are better in theory, the cooling ability of the 30W is why it is recommended, and probably always will be.


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