Advantages of using SAE 30?

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Pretty simple question: why do most small engines require SAE 30 oil instead of regular 5w-30 or 10w-30? I know they say 5w-30 and 10w-30 is recommended in cold temperatures because they flow better, but couldn't I just use it in higher temps too? Why even bother with the SAE 30?
 
the simple answer is most small engines are manufactured by briggs and stratton and they recommend sae 30 honda on the other hand recommend 10w-30 and you could also note that honda branded oil in australia is api sg a classification which is way out of date [superceded by api sh in jan 1996]so i would say there is no reason that you could not use 10w-30 or even 5w-30 i have been using 5w-30 for over 2 years
 
The conventional wisdom was than non multi grade oils did not have certain additives that would break down. Viscosity index improvers and maybe pour point depressants are additives that could break down under the high heat of an air cooled engine.

The result was an oil that retains it's viscosity.

Aircraft air cooled engines are similar. Typically, a single viscosity oil is used, such as Aeroshell 100 (50W).

Here in Florida, dino and multi grade users had far more generator failures after the hurricanes. Guess what part failed in nearly every case? The aluminum connecting rod. The oil was nearly always filled with aluminum metalic flakes for many hours before it finally quit.

Users of M1 15-50 synthetic had nearly "zero" oil related failures from what I can determine.
 
****, and others:

Indication of "SAE30" does not imply dino. I'm hardly shocked that B&S would find that any synthetic would work better than dino. What it does mean is that no VIIs are in the oil - synthetic or dino. The advantage is that there are no VIIs to shear down during the OCI.

Good synthetic stock SAE30s will have the same VI as multi-grade dino oils achieve with the use of VIIs.

Amsoil ACD and ASE are VII-free and dual rated SAE30/10W30. With no VII use they achieve the rating of 10W30. I've started using ASE in my summer OPE. Prior to that I used M1 10W30. I use GC in my snowthrower (1986 Tecumseh 8hp Snowking).

It would be a reasonable assumption, but I cannot confirm, that many group IV PAO synthetic 10W30s may indeed have no VIIs either and technically could be considered SAE30s. M1 10W30 HM should also make a good, premium OPE oil if you don't want to use something specifically single grade.
 
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I run Mobil 1 10-30 ep in my Honda LM and change twice per year. The synthetic runs smoother than conventional oil. Thinner oils dissipate heat better than thicker oils.
 
I have noticed that engines without oil pumps usually call for straight grade oils. I think without a pump moving the oil through the bearing the VIIs can break down.
 
Our snowblowers are the only small engines we have left, and I think they call for 10W-30. I've been running 5W-30 in them for the past four years. Are the just-below-freezing temperatures able to make that much of a difference in an air-cooled engine that multi-grade oils won't break down in the winter?
 
Once a snow blower engine get hot, the oil is 30 weight.
The 5W comes in play at start up. Many, if not most, snowblowers are spec'd for 5W-30.
 
Then shouldn't the same apply to lawnmower engines? Both are air-cooled and, other than orientation, the designs are fairly similar between snowblower and lawnmower engines of the same manufacturer.
 
My Toro tractor with Kohler engine says to use only SAE 30 if I'm planning on using it in 32* F or above temperatures. It says use 10w-30 if the temps are gonna be between 0-32*F and 5w-30 anything below that. Same thing with my Honda-powered Craftsman push mower. My Toro snowblower with Tecumseh engine is spec'd for 10w-30 or 5w-30 because the expected outside temperature is cold.
 
Yes, Squishy, that would apply to mowers as well.
I would point out though, that many here suggest Rotella 5W-40 for mowers and other summer OPE.
 
Then why are VIIs such a big deal with lawnmowers? Both engines are generally spec'd for 50-hour OCIs, and even then most owners just do yearly changes.
 
Originally Posted By: Squishy
Then why are VIIs such a big deal with lawnmowers? Both engines are generally spec'd for 50-hour OCIs, and even then most owners just do yearly changes.


Not sure why you're puzzled by this. It isn't that VIIs are any more or less of "a big deal" for snowthrowers, it's that the benefit of multi-weights for dedicated COLD WEATHER OPE outweighs any possible harm. No one should have a hard time understanding that snowthrowers and lawn mowers operate in different typical conditions and climates. The typical starting condition of a lawnmower is probably above 70F - not so for a snowthrower. True SAE30 DINO (which is what most people use if they use SAE30) would be pretty waxy at 0F.

As we've already discussed, you can get multi-weight rated oils that don't have VIIs as well.

Furthermore, some oils containing VIIs are more shear-stable than others. When a manufacturer makes a specification they write it for the lowest common denominator idiot who is going to put the cheapest [censored] they can find in the machine. The cheapest [censored] SAE30 is most likely going to be better for a lawnmower than the cheapest [censored] 5W30 in typical operating conditions and owner maintenance habits.

If you know you've selected a top quality, shear-stable multi-weight oil based on above-average knowledge and experience - knock yourself out and run it.
 
I was puzzled by the fact that 5W30 can run 50 hours in a snowblower, but lawnmowers "require" (to quote the OP) SAE30. From your post I gather that it's a case of SAE30 will hold up better, but 5W30 is still adequate (and obviously would be necessary for cold weather). So running 5W30 or 10W30 in a lawnmower should be fine as well.
 
We have been using left over 0W-30 Amsoil in the Lawnmower and Snow Blower.

Funny thing 2 years ago when look at snow blowers was that they recommended Synthetic oil if used below 32F. Uh a snow blower???
 
Originally Posted By: tmorris1
I run 5W30 synthetic in my lawnmower without any consumption issues.


With over 900 posts you know this, but consumption isn't the same concern as shearing but can be related and is worth pointing out to the OP.

To the OP, some folks have found they need to use SAE30 to prevent excessive consumption. Since, in theory, an SAE30 and a xW30 have the same weight at operating temperature, a lot of these engines' oil loss must be at startup and while warming up or due to shearing reducing the operating viscosity to a point where loss occurs at full temp.
 
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Originally Posted By: Squishy
I was puzzled by the fact that 5W30 can run 50 hours in a snowblower, but lawnmowers "require" (to quote the OP) SAE30. From your post I gather that it's a case of SAE30 will hold up better, but 5W30 is still adequate (and obviously would be necessary for cold weather). So running 5W30 or 10W30 in a lawnmower should be fine as well.


I look at it this way...20 ounces of 5w-30 for hard use in a snow blower during 30 degree f weather vs. 20 ounces of straight 30wt for hard use in a mower during 85 degree f weather. Both engines are air cooled. Both oils are rated to be a 30wt at 212 degrees f. I feel however that the oil in the snow blower has a 55 degree cooler advantage as far as running temp and it's associated effects on the oil (and that's assuming the cooling fins on the mower aren't buggered-up with clippings) - both in viscosity and extremes for which the oil and additives itself have to contend with. The multi-grade for cold starting would serve also as a plus in terms of aiding initial lubrication and economy/emissions/performance for the snowblower. The straight weight has a more stable viscosity without dependence of VII's, though suffers by way of lower VI compared with a multi-grade.

Above assumes regular mineral oil base stocks. Going "synthetic" changes things as others have noted - likely no dependence on VII's for enabling a high VI, multi-weight oil.

Take care.
 
Exactly CK,

The snow blower is not likely to run in 90+ degree heat, while a lawn mower will spend the majority of it's life, being cooled by air that is 50-70 degrees or more warmer.

That does make a difference.

It would be a great study to compare the engine temperatures at various ambient temperatures to see how much of a difference ambient temperature makes during engine operation.
 
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