John Deere 318 HDEO 15W 40 Diesel Oil

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Well, I'm posting my first one here. I've got this mower with an 1985 Onan B43G engine. I've owned this 9 years (about 1400 hours on it), and always used 30W only in It-usually JD Torq Guard or Pennzoil. After getting more interested in researching oils for my F150 4.6L and Jeep Wrangler 4.0 here in BITOG, I am wanting to switch to 15W 40 which is spec'd in the owners manual (also specs 20W 40 but not too available). I've read a lot of threads on this type of oil, and can mostly only find ones like Supertech, Rotella, Delo, Delvac, etc., but most are diesel only rated. I read that Rotella dropped their gas ratting some years ago, so maybe it could be the exception and really still be fine for gas. I'd really like to go with a full synthetic for better engine heat management which I've read about on BITOG. I've got the usual John Deere 318 cooling issues covered with the grommet around the oil filter replaced, and a new firewall insulation kit coming. I'd also like to use the most shear resistant applicable oil. Am I safe to use this type of HDEO without having a gas rating? I'm just trying to hedge against my lack of knowledge of oil, thinking there may be something I'm not considering. I put around less than 50 hours per year on this mower in Tennessee, so a bit hot during summer. Right now, I don't use it in the winter, but am looking for a snow blade for winter. Oil and filter (JD or Wix) changed at the end of each sumner season.
 
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HDEO is fine in small engines or even old cars or race cars without a catalytic converter, generally the only reason why an HDEO won't have a gas rating is that it contains too much ZDDP and the phosphorus level exceeds that allowed by modern API limits for gasoline oil, the limits are there to prolong the life catalytic converters and keep them running as far above threshold as possible to reduce air pollution, since phosphorus poisons the catalytic material, in a small engine there's no worries since there's no catalyst to poison.
 

SwedeFP

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Thanks for both responses. Now, I'll try to figure out which 15W 40 full synthetic has the best shear resistance. I'm still a little curious about 20W 40 oils, since that multi viscosity is given in the manual. The only ones I've found are for motorcycles, and higher priced, except less so for the Supertech. I'm developing a new habit of more time than usual checking out oil in stores that carry it. My local TSC has a nice broad inventory (even a Traveller 30W HD with still an SG rating). Got to get to the closest Rural King to check out their oils.
 
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Thanks for both responses. Now, I'll try to figure out which 15W 40 full synthetic has the best shear resistance. I'm still a little curious about 20W 40 oils, since that multi viscosity is given in the manual. The only ones I've found are for motorcycles, and higher priced, except less so for the Supertech. I'm developing a new habit of more time than usual checking out oil in stores that carry it. My local TSC has a nice broad inventory (even a Traveller 30W HD with still an SG rating). Got to get to the closest Rural King to check out their oils.
Does the engine have a problem with shearing the oil?
 

SwedeFP

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Well, I'm not really sure. I'm just thinking it is probably hard on oil as these are just air cooled, and with this old of an engine, more fuel dilution. It smokes a little on startup. This is the best mower I've ever had, and really more like a small tractor with stout frame, hydraulics front, middle, and rear. I love this GT, and will even rebuild the engine if it ever fails.
 
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Well fuel dilution and oxidation resistance are different than mechanical shear. The "gas rating" would only really be applicable to vehicles with emissions equipment which doesn't matter with a lawn mower. What you have been using is fine.
 

SwedeFP

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I looked at the Plus 50, but it's not synthetic. I was hoping going with a synthetic would help keep the oil temps down.
 

SwedeFP

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Well fuel dilution and oxidation resistance are different than mechanical shear. The "gas rating" would only really be applicable to vehicles with emissions equipment which doesn't matter with a lawn mower. What you have been using is fine.
I'm learning, and thanks for that info. I wanted to choose one to reduce loss of viscosity between changes to avoid less oil being burned. The manual even says to expect more consumption with a 5w 20 (?).
 

SwedeFP

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I might try that, but would a 20W 40 be better? If the lowest viscosity started out at 20 and would rise to 40, it would match the manual which specs only as high as 40. It even allows for straight 40, but only of higher ambient temp is 68 F.
 
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I might try that, but would a 20W 40 be better? If the lowest viscosity started out at 20 and would rise to 40, it would match the manual which specs only as high as 40. It even allows for straight 40, but only of higher ambient temp is 68 F.
That is not how the winter ratings work. The oil does not "start out" as a 20 and "rise" to a 40, all oils thin as the temperature increases. They do not get thicker.

The 15W-40 you are using is completely fine.
 
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Any 15W-40 in an Onan B43 (E or G) or an Onan P218 would be no problem. These engines are oil designs... reliable workhorses but they love HDEO.

Couple points I would like to share. Is your oil consumption definitely that or could it be a leak? Do you have any oil leaks? The B43G should have an oil filter if I'm not mistaken -- and the oil filter housing gasket on these leaks and can coat the side of the engine with oil.

Additionally, the Onan's use the forced air of the flywheel to cool the engine. It is important to keep the engine clean of mouse nests, build up, etc. I would recommend taking the side tins off and blowing the engine out.

Some other related points, the underneath belly screen on the 316 helps keep large grass clippings out from going through the engine's cooling fins. The engine compartment insulation is also important as it makes sure the engine doesn't suck hot air back in to cool itself.
 

SwedeFP

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That is not how the winter ratings work. The oil does not "start out" as a 20 and "rise" to a 40, all oils thin as the temperature increases. They do not get thicker.

The 15W-40 you are using is completely fine.
I tried to read about viscosity before posting, and the links I found said that multiviscosity oils are at the lower weight and then thicken or "prevent from thickening" for hotter temperatures. If they don't get thicker, how do they reach in this case 40?
 
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I tried to read about viscosity before posting, and the links I found said that multiviscosity oils are at the lower weight and then thicken or "prevent from thickening" for hotter temperatures. If they don't get thicker, how do they reach in this case 40?
A 40-grade oil is always a 40-grade oil. The 15W-40 thickens somewhat less than a monograde 40 oil when cold to achieve the multi-grade winter rating. Winter ratings would be better described without numbers to prevent this misunderstanding.

Again no oil thickens as it warms up. Every oil thins as the temperature increases.
 

SwedeFP

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Any 15W-40 in an Onan B43 (E or G) or an Onan P218 would be no problem. These engines are oil designs... reliable workhorses but they love HDEO.

Couple points I would like to share. Is your oil consumption definitely that or could it be a leak? Do you have any oil leaks? The B43G should have an oil filter if I'm not mistaken -- and the oil filter housing gasket on these leaks and can coat the side of the engine with oil.

Additionally, the Onan's use the forced air of the flywheel to cool the engine. It is important to keep the engine clean of mouse nests, build up, etc. I would recommend taking the side tins off and blowing the engine out.

Some other related points, the underneath belly screen on the 316 helps keep large grass clippings out from going through the engine's cooling fins. The engine compartment insulation is also important as it makes sure the engine doesn't suck hot air back in to cool itself.
Thanks for posting that information about these old engines. I end up adding maybe an ounce or two between mowings. I've recently looked at that gasket type part that goes around the oil filter to seal off the air that could come out of the engine compartment instead of going mature toward cooling the right cylinder, and saw no leaks. I keep a piece of cardboard under it, and see no oil spots.
I kind of baby this mower, as after mowing I use a leaf blower on the deck top, through the air grates on the side plates and around the battery, then through the front grill then the top of the engine. I've never had a grass build up yet. I keep the belly screen on, and clean it. Heck. I even park it in a cool basement, and then open the hood and put a fan on high at the front grill and blow air over the cylinders. Now, I'll add to that the HDEO 15W 40. My insulation is shot, but have a new kit coming from John Lang who makes them in three pieces so no engine removal is required.
 

SwedeFP

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A 40-grade oil is always a 40-grade oil. The 15W-40 thickens somewhat less than a monograde 40 oil when cold to achieve the multi-grade winter rating. Winter ratings would be better described without numbers to prevent this misunderstanding.

Again no oil thickens as it warms up. Every oil thins as the temperature increases.
Thanks again, and would you recommend a link, so I can read more on this to better understand?
 
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