Which oil to use for lawn mower?

[Cliffh]

I do the maintenance on our 2 riding mowers and a zero turn.  The zero turn is new, only 5 hours on the new engine*.  The engines are Briggs, Kohler and Kawasaki, all twins in the 25hp range.  I've been doing the oil and filter changes on the two riding mowers at 25 hours, the ZT got an oil change at 5 hours and will be on the same 25 hour cycle as the other two. 

I've been using Castrol 30w for the riders, Castrol 10w30 in the ZT.  Next oil change, the ZT will be getting 20w50, that'll be good from 32* to over 100* according to the manual.

Looking around tonight checking prices etc. I ran across an ad for Castrol Synthetic for motorcycles.  All these years working on cars, bikes and mowers and it just now occurred to me that oil for air cooled motorcycles just might be good for air cooled mowers.

Thought I'd get input from y'all before going that route.




*The mower itself has 25 hours on it.  At about the 20 hour mark, DW was mowing the back yard when the dipstick tube came loose.  She didn't notice until break time, by then the engine was literally toast.

[Bogie]

A lot of bikes run wet clutches... I'd use whatever the mower's manual says to use.

[Cliffh]

All any of the manuals mention is the viscosity and API rating.  No mention is made of conventional vs synthetic or auto vs motorcycle oils.

[zahc]

 There is no bad oil anymore. The standards have evolved to that point. Use any modern engine oil.

[Brad Johnson]

Don't use motorcycle oil. Additive packages designed for wet clutch applications may not play well with your mower engine's innards.

Use fhe mfg's recommendation. If you want a little extra protection go full synthetic or just do more frequent oil changes.

Do not, under any circumstance, extend service intervals for convenience or perceived savings. That's a surefire way to shorten service life. Usually by a lot.

Brad

[Kingcreek]

Full synthetic in everything.
A senior project engineer worked for Porsche developing racing and aircraft engines then retired from Caterpillar gave me that advice.

[Ben]

Full synthetic in everything.
A senior project engineer worked for Porsche developing racing and aircraft engines then retired from Caterpillar gave me that advice.

Yup. The price delta is small enough that it's not worth it to go dino. My philosophy is that oil changes are one of the cheapest and best longevity things you can do for your engines.

I just put 5W-30 synthetic in all the small engines and my Honda Rancher, and the Polaris Ranger gets 5W-40 synthetic diesel oil in the Winter, and 15W-40 in the Summer, because Polaris is weird, and their oil is ridiculously priced.

[Bogie]

Another thing to consider is detergent vs. non-detergent... A lot of small engines will require a non-detergent oil... That seems to be related to filtration, or lack thereof...

[HeroHog]

Another thing to consider is detergent vs. non-detergent... A lot of small engines will require a non-detergent oil... That seems to be related to filtration, or lack thereof...

THIS! Many modern small engines DO have filters; again, as someone else stated earlier, check your owners manual!

[tokugawa]

Cross reference the owners manuals and see if there is one oil type that will satisfy all the requirements and go with that.
Motorcycle specific oils are different, in that they lack some friction reducing additives, to keep the wet clutches from slipping.  At least they used to be, my info could be out of date.

[AZRedhawk44]

Royal Purple obviously.

Now, what tires to use for lawn mower?   

[Brad Johnson]

Now, what tires to use for lawn mower?   

Hoosier.

Brad

[Cliffh]

Unfortunately, the manuals aren't very helpful when it comes to choosing oil.  They do mention using a non-detergent oil.

The manuals for my equipment suggest a 50 hour oil change interval.  One manual (for a now defunct mower) had suggested a 100 hour interval.  I've cut that back to 25 hours with a filter change at the same time.  The first engine in my mower got 50 hr changes, it died at 350 hrs.  The current engine is looking for the next oil change at 1,050 hrs - on a Briggs.

Tokugawa mentioned the lack of some lubricating properties in the motorcycle oils - which I had forgotten about.  That right there is enough for me to stick with the auto oil I've been using.

I could get away with using straight 30w in all the engines, but the Kawasaki manual suggests the engine might be happier with 20w50.  No problem keeping a couple different oils around, there's not much possibility of my confusing them.

As for tires, I'll be sticking with the Goodyear's. 

[Bogie]

About the only non-detergent oil we carried was a straight 30 weight... and we kept the quarts in the back. If you go to an O'Reilly, tell the counter guy SPECIFICALLY non-detergent SAE 30 - the house brand 30 is a detergent oil.

[Cliffh]

Bogie

Good to know.  Thanks.

[Bogie]

https://www.oreillyauto.com/detail/c/pure-guard/pure-guard-non-detergent-motor-oil-30w-1-quart/pgd0/nd30qt?q=sae+30&pos=11

[JTHunter]

Cliffh - I don't believe that using 20W-50 is a good idea as that oil remains too thick at startup.  It also increases the amount of "resistance" the moving parts have to push against.  You will also use more gas and that's why most cars now recommend 5W-30 year round.  You can try using 10W-40 which will give you the lubricity you need at start up but a little extra thickness (40) during the heat of summer.

[Cliffh]

I was basing the 20w-50 on this paragraph from the manual:

Although 10W-40 engine oil is the recommended oil for most conditions, the oil viscosity may need to be changed to accommodate atmospheric conditions. Using 20W-50 oil in higher ambient temperatures may reduce oil consumption.

The 10w-40 is rated for use from 14*F to >104*F, 20w-50 is rated from 32*F to >~110*F.  We'll rarely run it in any weather below 40*, and I highly doubt it'll ever be run below 32*.  On the other hand, it will be run in temps above 100* - too many days a year are above 100* to not mow in those temps.  (Gotta love TX summers).  I may I'll most likely run the 10w-40 until it's got more hours on it, (it only has 5 hours on it right now), let things loosen up a bit.

I was incorrect earlier when I said the manuals recommended a 50 hour interval for oil changes on the zero turn.  The manual actually recommends a 100 hour interval or once a year.  Yeah, no.  I'm sticking with the 25 hour interval.  Oil & filters are cheap compared to a new engine.   

I have destroyed one expensive engine by using too thick an oil in cold weather - broke at least one of 8 pistons.  (Didn't tear into it to find out how many).  If this one absolutely has to be run below 32*, I'll change the oil first.  Yes, it'll be thick and drain slow.  Heaters and time should take care of that.

[JTHunter]

Ah yes.  Gotta love those "summers".  Got a friend that moved to Haslet from ILL-ANNOY several years ago and we talk about every week still.  He keeps me "updated" on the weather down there.