Air Cooled Engines and SAE 30?

[ffxfina3]

So, I've just purchased a 2004 Gravely 34Z with 182 hours on it. Naturally, the first thing I'd like to do is change the oil.

Reading through the owner's manual for the Kawasaki 15HP engine that is on this thing, Kawasaki states that in my temperature range, to use either SAE 30, 10w-30, or 10w-40. Then, as many of you are already familiar, they state that I should expect some oil consumption if using a multi-grade viscosity oil.

So, what is it about this Kawasaki engine that causes a multi-viscosity oil to get burned up? Is it because it is air-cooled, rather than liquid-cooled? And if so, why? Or is there something else going on here?

Thanks,
Bryan

 

[widman]

The first thing weird is that SAE studies show less oil use with multigrades than monogrades.

Assuming it is a 4-cycle (I'm not familiar with it) the only thing that could destroy a multigrade would be small diameter high speed gears to synchronize valves and crank. This can shear the oil.

2-cycles shear the oil in the ports.

 

[Bror Jace]

Bryan, it's the high temps in OPE engines in general that can be hard on oil, depending on the application, as opposed to your engine in particular. Many Briggs & Stratton manuals I've seen say the same thing.

High temps will thin/shear the oil to the point where more of it will slip past rings, valve guides, etc ...

Then there is what widman is saying about SAE studies. I can't really comment on that.

 

[ffxfina3]

Thanks javacontour,

I also just ran across this older BITOG thread from 2008 which was helpful, too:

Advantages of using SAE 30?

The general theme in that thread seems to suggest that it is the presence of VII in most multi-viscosity oils that are the main problem in an air-cooled engine. And apparently, according to this prior thread, Amsoil is/was the only manufacturer making a synthetic 10w-30 that didn't have VII added.

Does anybody know if there are any other synthetic Xw-30 oils with VII?

Thanks again,
Bryan

 

[ARCOgraphite]

Just pick an HD oil with good HTHS performance (>3.5cP) without going overboard in kv100. The hths spec shears the oil through a nozzle at 150deg C (multipass) and then tests its viscosity. Oils without VII will tend to shear less at high temp high shear. VII are a polymer not a lubricant.

 

[05ChevyI5]

I would use Rotella T5 10W-30.

 

[boraticus]

I own a 2002 Husqvarna riding mower with the same 15 h.p. Kawasaki engine. I run 10-30, 10-40 or 15W40 off the shelf leading brand oil (Shell, Imperial Oil, Quaker State etc). Right now it's got Shell 10W40 in it because I got it for $1.79 a liter.

The mower gets one oil change annually and it works approx. 50 to 60 hrs. yr. It has around 400 hrs on it. No oil consumption at all. None. Engine still runs like the day I bought it. It's a push rod overhead valve fan cooled twin and one of the nicest engines I own.

Other than annual oil changes, oil filter change every three years, spark plug cleaning, air filter change and blowing grass out of the cooling fins, I've had to do nothing else to it. I haven't even had to adjust the valve lash.

Kawasaki engines are among the best for OPE applications. They are very robust and not fussy about oil. Use any leading brand name oil (in viscosity range) you can get for the least amount of money.

 

[kcfx4]

i dont have a scientific reason, strictly opinion. I run vwb sae30 in both of my aircooled kawasaki engines, and i have a 17hp single cylinder that is 16 yrs old 2K+ hrs, never been into, never used any oil, and all its ever had is vwb sae30. i wish more ppl would buy sae30 as its getting harder to find.

 

[dwendt44]

Most air cooled engines are set up 'looser' that liquid cooled.
That and the higher temps., higher oil temps., and the 'thinner at room temp. of multi-vis oils allow a little oil to get past the rings before the piston and rings expand as the engine heats up.

That's my story and I'm sticking to it.

 

[ffxfina3]

Thanks for the replies everybody. Much to think about.

Cheers,
Bryan

 

[660mag]

They have tapered cylinders that expand to parallel. So they will use oil until they get hot. The oil loss happens during warm up only. Once it's hot the oil is the same as a mono. that is the reason you have to warm up an airplane engine too. Just check the level before each use and it would be fine.

 

[doitmyself]

Interesting stuff, 660mag.

Also it's interesting that boraticus and KCFX4 have provided anecdotal evidence (informal account of evidence, not to be taken as derogatory) that not only do multi weights work, but they have had good luck going against the school of thought of needing an HDEO vs. a "weaker" automotive oil.

Thanks for sharing. Boraticus, my Exmark will be "blue with envy" this mowing season.

 

[JTK]

Awesome ZTR Bryan. You have to love anything Gravely. I hear these ride and handle real well. They offer lots of up/down deck float too which is really good on rough stuff.

Joel

 

[beanoil]

Originally Posted By: widman
The first thing weird is that SAE studies show less oil use with multigrades than monogrades.

Assuming it is a 4-cycle (I'm not familiar with it) the only thing that could destroy a multigrade would be small diameter high speed gears to synchronize valves and crank. This can shear the oil.

2-cycles shear the oil in the ports.

What? Multigrades have a tendency to shear the VI's that make it multigrade. Two stroke oils are straight grades, most are 30 weight, but there are 20 weight (Castrol TTS), 40 weight, (Kawasaki two stroke by Citgo) and 50 weight (Castrol A747). There are no VI's to shear.
I think OPE engines have a tendency to consume multigrades because over time, the oil loses it's high temperature viscosity, and there can be some fuel dilution. FWIW, my 20 year old Snapper (Briggs 8 horse) has had a steady diet of Rotella 30 weight, and still runs like new.

 

[doitmyself]

bean, are you going to continue using the Rotella 30w even though they took the gasoline rating off of it?

 

[GT245]

Originally Posted By: doitmyself
Interesting stuff, 660mag.

Also it's interesting that boraticus and KCFX4 have provided anecdotal evidence (informal account of evidence, not to be taken as derogatory) that not only do multi weights work, but they have had good luck going against the school of thought of needing an HDEO vs. a "weaker" automotive oil.

Thanks for sharing. Boraticus, my Exmark will be "blue with envy" this mowing season.

my first post here, but kcfx4 noted a sraight weight, not multi, and i tend to prefer sae30 conventional myself, as i believe its less likely to shear

 

[ffxfina3]

Originally Posted By: JTK
Awesome ZTR Bryan. You have to love anything Gravely. I hear these ride and handle real well. They offer lots of up/down deck float too which is really good on rough stuff.


Thanks JTK. I'm looking forward to mowing this year! Regarding the comments about the oil, I ordered two quarts of Amsoil ASE 10w-30/SAE 30. I've not been a big Amsoil user through the years (only tried it once in our '03 Ford Focus). But this particular stuff really seems to be a top notch oil without any VIIs. I've got a Fleetguard Filter to go with it.

Thanks,
Bryan

 

[doitmyself]

Originally Posted By: GT245
my first post here, but kcfx4 noted a straight weight, not multi, and i tend to prefer sae30 conventional myself, as i believe its less likely to shear


I posted that mistake just to lure you in to BITOG! Welcome to the lunacy and thanks for correcting the error. I meant to write that Boraticus is having good results with multi-weight and both of them (KCFX4) are also only using regular automotive oil (vs. HDEO).

 

[boraticus]

Originally Posted By: doitmyself
Originally Posted By: GT245
my first post here, but kcfx4 noted a straight weight, not multi, and i tend to prefer sae30 conventional myself, as i believe its less likely to shear


I posted that mistake just to lure you in to BITOG! Welcome to the lunacy and thanks for correcting the error. I meant to write that Boraticus is having good results with multi-weight and both of them (KCFX4) are also only using regular automotive oil (vs. HDEO).




Nowhere in the Kawasaki engine manual does it specify that HDEO is required. Considering that there is no transmission involved, there aren't any gears that would contribute to oil shearing. Accordingly, I have no reservation using an automotive 10W40 oil.

Below is an excerpt from the ForumulaShell product description:

"Some European vehicle manufacturers, however, recommend the 10W-40 grade, particularly for high temperature operation."

Accordingly, a quality 10W40 off the shelf brand oil selling for $1.79/liter is not only a good deal, it's also more than adequate for the job.

 

[doitmyself]

Originally Posted By: boraticus
Nowhere in the Kawasaki engine manual does it specify that HDEO is required.


But, my relatively new manual specifies Api service classification :SF,SG,SH,SJ, inferring a higher additive level oil.

There are two schools on this oil choice issue. You have demonstrated that using non HDEO oil has worked well for you.