Oil Choice for

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JD L111 with a B&S 20HP twin which has oil filter and oil pump. Presently using PP 10w30. Would there be any benefit to switching to Rotella T6 5w40? I have a small yard here in Florida and engines see only 45 minutes running per mowing. Ed
 
Originally Posted By: Eddie
Since B&S recommends 5w-30 synthetic or 10w-30, I'm curious why you recommend a 15w oil?
Because the 15W-40 is a superior oil for an air cooled engine. Especially in warm weather.
 
Oils with less spread between the two numbers have less tendency to shear in rough hot applications like air cooled engines. Thus 15W-40 is a better oil in air cooled engines in the hot Florida heat compared to 5W-40.

Mobil 15W-50 would still be a better choice.
 
I'll reiterate some of the good advice given above:

"Since B&S recommends 5w30 synthetic or 10w30, I'm curious why you recommend a 15w oil?"

Because they have no idea where their engine will be run ... Minnesota or Florida? Heck, sometimes the manual I get with the engine (separate from the rest of the machine) suggests they don't even know what kind of machine their engine is bolted on. Their recommendation is usually some sort of compromise.

"Oils with less spread between the two numbers have less tendency to shear in rough hot applications like air cooled engines. Thus 15W-40 is a better oil in air cooled engines in the hot Florida heat compared to 5W-40."

Yes ... cheaper and less resistant to thermal shearing. No benefit to the 5W-40 in high heat conditions.

"Mobil 1 15W-50 would still be a better choice [for Florida]."

I'm not sure about that. Eddie says he only runs his machine for 45 minutes at a time. If he was going for double that or more, you might be right. I know that's Cujet's story ... and he's sticking with it.
 
They don't recommend over a Xw30, so I would use T5 or Delo XLE in 10w30 myself. 50 weight oil seems way too thick for this application to me.
 
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vronline, I would agree with your recommendations for Kansas ... but for sustained Florida heat, those lubricants probably won't cut it. Cujet is a contractor that works in Jupiter, FL and has tortured many OPE units to death. The oil that makes 'em last the longest is M1 15W-50.

Question for Cujet if he is lurking is, does that recommendation hold true for both splash and pressurized motors?

In the Northeast, even in summer, I would use an HDEO, synth or semi-synth 10W30 year 'round in a new-ish engine. If after a few seasons have passed and you start to notice oil consumption, then, I'd step up to an XW-40 for the warmest months. I used 15W-40 in a Honda Tractor (liquid cooled) and it ran flawlessly on 15W-40 from March to November for over 20 years. Insides were squeaky clean to boot! I probably could have gotten the same results from an 10W-30 HDEO ... but there's no denying the 15W-40's results.
 
Originally Posted By: Eddie
Since B&S recommends 5w30 synthetic or 10w30, I'm curious why you recommend a 15w oil?
On B&S recommendation chart, you can use straight 30 oil above 40 degrees. So if a 30w can work, a 15w wouldn't be any problem, especially down there in Florida.

Originally Posted By: JimPghPA
Oils with less spread between the two numbers have less tendency to shear in rough hot applications like air cooled engines. Thus 15W-40 is a better oil in air cooled engines in the hot Florida heat compared to 5W-40.

Mobil 15W-50 would still be a better choice.
JimPghPA said:
While the shearing is true, also consider that 15w40 is conventional oils and 5w40 are synthetics. They both may have the same amount of VII's and therefore there tendency to shearing would be the same. If you want to go synthetic, then T6 5w40 or Mobil 1 15w50 are both good choices.
 
Thanks for the input people. To reiterate; since I only mow for approx. 45 minutes per time, I am inclined to stick with B&S recommendations of a 10w30 viscosity as vronline & sw99 use. However; your comments suggest that maybe a Rotella T5 (10w30 diesel oil) might offer some real advantages over my PP 10w30. What do you folks think? Ed
 
Not so fast.

I was waiting for someone to recommend Delo Severe Duty 15W30. If you google "Delo Severe Duty", it fares very well in independent hot weather testing compared to other synthetic and HDEO's (10W30, 5W40 and 15W40 viscosities).

Delo 15W30 Severe Duty satisfies the manufacturer recommendation for a 30 weight oil. In theory, it should perform as well as other 5W40 and 15W50 synthetic recommendations in a hot weather application - for less $$$. I bought a 4 quart container on sale for about $13. It will be going my 21 HP Kawasaki powered, air cooled, Cub Cadet lawn tractor. Also my air cooled generator. Subaru Robin powered, 8000 watt (10000 peak). Both throw off a lot of heat.
 
For Briggs engines: In customers engines that just want an oil change and dont specify what they want, SAE30. In my own Briggs engines, synthetic 10W30 in new engines or SAE30 in old engines, especially older worn out engines or those with unknown maintenance history. That's what I do.

If the engine is used commercially, then 15W40. If used by a homeowner for normal use, then a 30 weight is fine.
 
It gets hotter here in Illinois than Florida at times. I have used M1 10-30 in all my OPE for at least 20 years, never a problem.
 
Originally Posted By: Eddie
I tentively decided on running T5 10w30 and will get it at Walmarts. Ed


Great choice, you wont be disappointed. This is a robust HDEO that will do an excellent job.
 
"I tentively decided on running T5 10w30 and will get it at Wal-Mart"

Just be sure to check it each time before mowing until you get a really clear trend on consumption. If consumption strikes you as too high, consider switching to the same oil in 15W40.
 
Bror Jace, You obviously haven't been here during summer... 5w or 10w30 will be fine, particularly a thicker HDEO like Delo XLE or Rotella T5.
 
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