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Onan BF-MS 16hp oil. 15w40 or 30w????

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Brad-RT/13

· SEARS TRACTOR COLLECTAH
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Discussion starter · #1 ·
Ok guys, This has been driving me crazy. I'm trying to figure out what type of oil to use in my '73 Sears SS/16. Well I've been reading alot of older forums on what oils to use in onans. Well, So far It seems most people run 30w year round. And some run 10w30 all summer. But the those that run 10w say that oil consumption is quite high, And the ones running 30w see little to no oil consumption. I also found an oil viscosity chart: 32-100 use 30w, 10-100 use 15w40, and 0-80 use 10w30 or40. So when I checked at wal-mart they had Rotella 10w40 and 15w40, But no 30w. However my local TSC has 30w in pennzoil, valvoline, and castrol. Any recommendations would be greatly appreciated! Thanks -Brad
 
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#2 ·
I use 30wt all year round. Never had an issue. If your Onan does not have an oil filter make sure you use non-detergent oil too! The manual does state in cold weather that you can use 10w30 instead to compensate for the cold temp and aid in startup. I have always runs straight 30 though, and never really had an issue.
 
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Discussion starter · #3 ·
GT_80 said:
I use 30wt all year round. Never had an issue. If your Onan does not have an oil filter make sure you use non-detergent oil too! The manual does state in cold weather that you can use 10w30 instead to compensate for the cold temp and aid in startup. I have always runs straight 30 though, and never really had an issue.
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Ok thanks alot GT-80! Much appreciated.
 
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#4 ·
One thing to take into consideration when changing oil in an old 1970's tractor is it very likely was operated with leaded gas back in the 1970's until they switched to unleaded gas. A good flushing of the crankcase with fresh clean oil should help. You might try using a lead inhibitor also.

Another thing to do is determine the climate you will be operating the tractor in. You might consider using 5W 30 oil in Maine during the winter. A section from the manual concerning motor oil follows and it says to use detergent oil. You can point and click on the image to enlarge it so it will be easier to read.

I have been using high quality straight SAE 30 motor oil in my climate and I have heard a lot of other people use SAE 30 also. An Onan mechanic I spoke with a few years ago said he uses Castrol SAE 30 when he services Onan engines.
 

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Discussion starter · #5 ·
Plowthesidewalk said:
One thing to take into consideration when changing oil in an old 1970's tractor is it very likely was operated with leaded gas back in the 1970's until they switched to unleaded gas. A good flushing of the crankcase with fresh clean oil should help. You might try using a lead inhibitor also.

Another thing to do is determine the climate you will be operating the tractor in. You might consider using 5W 30 oil in Maine during the winter. A section from the manual concerning motor oil follows and it says to use detergent oil. You can point and click on the image to enlarge it so it will be easier to read.

I have been using high quality straight SAE 30 motor oil in my climate and I have heard a lot of other people use SAE 30 also. An Onan mechanic I spoke with a few years ago said he uses Castrol SAE 30 when he services Onan engines.
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Ok thanks man, I think I will just run Napa 30w in it for now. Because its the only non detergent oil in my area. I do have access to alot of the big brand 30w's but they're all detergent oils, And everyone says not to use detergent oil. Thanks. -Brad
 
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#7 ·
As long as the engine hasn't become sludged up inside,you can run detergent oil in it with no ill effects...if it were run on non detergent for a long time it could have a lot of crud at the base of the oil sump that could be loosened up and sent thru the engine when a detergent oil is used,that is when you'll have trouble...but if you flush it out good you most likely wont have any issues whatsoever..

Diesel rated oils like Rotella have a higher detergency than other motor oils intended for automobiles,but can be used in all engines provided they aren't sludged up---the diesel oil has more zinc which keeps cam lobes from wearing out quickly,many other oils no longer have it,or so little it dont help prevent wear..it also keeps the dirt in suspension better,a desireable thing with the soot diesel fuel creates...

I have flushed many small engines out with diesel fuel or kerosene,or mineral spirits,then used detergent oils with no ill effects,and I prefer to use 15W-40,its good down to about 15 degrees and since I have two diesel trucks its easier to just buy ine type of oil and use it in everything...I find 15W-40 doesn't get burned as fast as other oils if your engine uses a bit of oil,and it protects better...you can get 30W diesel oil just about anywhere,places like Wamart have 2 gallon jugs for about 15 bucks--a place near me that sell semi truck parts often has 5 gallon pails of 30W and 15W-40 on sale for about 35 bucks...

I wouldn't worry about harming your engine--my theory is we never know what the former owner(s) may have used for oil,or how often they changed it,etc--so any damage has already been done long before I owned it!...and whatever I use aint gonna hurt it any worse!--at least I flush the engine out and put good oil in it ,thats probably way more than the former owners did for it...
 
#8 ·
I think if they have had detergent oil in them in the past it is ok to run it now because all the contaminents have been flushed out (hopefully) - you never know what the last guy ran in it for oil. One of my Onans has 10w30 detergent oil in it right now(remembering my last change, thats all I had), and I haven't had any issues with it.
 
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#9 ·
They say to use the non-detergent oil in the transaxle. Use detergent oil in the engine. The climate you live in is where they use SAE 30, 5W 30, or 10W 30 motor oil. You typically use SAE 30 in a warmer climate. A lot of the memebers here have a proven track record with the oil they have used in the climates they live in.
 
Discussion starter · #10 ·
Tractor-Holic said:
As long as the engine hasn't become sludged up inside,you can run detergent oil in it with no ill effects...if it were run on non detergent for a long time it could have a lot of crud at the base of the oil sump that could be loosened up and sent thru the engine when a detergent oil is used,that is when you'll have trouble...but if you flush it out good you most likely wont have any issues whatsoever..

Diesel rated oils like Rotella have a higher detergency than other motor oils intended for automobiles,but can be used in all engines provided they aren't sludged up---the diesel oil has more zinc which keeps cam lobes from wearing out quickly,many other oils no longer have it,or so little it dont help prevent wear..it also keeps the dirt in suspension better,a desireable thing with the soot diesel fuel creates...

I have flushed many small engines out with diesel fuel or kerosene,or mineral spirits,then used detergent oils with no ill effects,and I prefer to use 15W-40,its good down to about 15 degrees and since I have two diesel trucks its easier to just buy ine type of oil and use it in everything...I find 15W-40 doesn't get burned as fast as other oils if your engine uses a bit of oil,and it protects better...you can get 30W diesel oil just about anywhere,places like Wamart have 2 gallon jugs for about 15 bucks--a place near me that sell semi truck parts often has 5 gallon pails of 30W and 15W-40 on sale for about 35 bucks...

I wouldn't worry about harming your engine--my theory is we never know what the former owner(s) may have used for oil,or how often they changed it,etc--so any damage has already been done long before I owned it!...and whatever I use aint gonna hurt it any worse!--at least I flush the engine out and put good oil in it ,thats probably way more than the former owners did for it...
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Hey thanks alot for that info man. I think thats exactly what I'm going to do with this one. The guy I got this from said his dad bought it new in '73, He told me this was his dads prized possession until he gave it to his son in 2001. He said he remembers his dad always changing the oil, air cleaner, and rear end oil on a regular basis, Which has to be true because in person this tractor is in really good condition. I think what I'll do is run the napa 30w for a bit, and then drain it and put in some Rotella 15w40, since its just a little bit thinner than 30w, The engine shouldn't use to much oil.
 
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#13 ·
I always use detergent HD30 in all small engines. Non Detergent is old old school for engines, I would not use it in any engine. It won't hurt anything but there are a lot better oils to use.

The only reason they spec. non detergent for the trans is so it don't foam, and there is nothing to clean in the trans, unlike a dirty gas engine.
 
#14 ·
When I was working in auto parts stores,the factory rep for Wolf's Head oil told me that "Non Detergent"oil made after the mid 60's had SOME detergent in it,just enough to satisfy the needs if engines being made in that era..

.up until then, oils were mostly straight weight, and had to be changed at every season to allow for cold starts--then multi-weight oils were introduced,and detergents added to keep engines cleaner inside...
He said since a lot of "clueless" people might buy ANY oil and dump it in a newer car,so the "non detergent"oils were modified, and a bit of detergent was added to them >just in case"..non detergent oils I see sold now have the lowest ratings as far as anti-wear and resistance to breaking down--one label I read said "NOT for use in any engine produced after 1932 !..had a rating of "SA" on the label...
(A customer brought 5 quarts of it to my friends shop when she wanted an oil change--he showed her the label and she said "eh--my dad says :eek:il is oil"--its all advertising hype!--just use it,my cars a "junk" anyway":rolleyes:)--so I can see why they put that disclaimer on the label,but whetherit will actually harm a newer engine remains to be seen!)..

I was also told most non-detergent oils were mineral based oil (and many still are)--versus todays oils being derived from petroleum or synthetics..he said mineral oils dont lubricate quite as good ,and can go "sour" after a long time..he reccomended flushing the crankcase well in any engine suspected of having used non detergent a long time and using a good multi-weight or SAE 30 detergent oil,and said he used diesel rated oils in all his vehicles and yard equipment...

Its nice when you can be sure an old tractor or engine had regilar maintainence and oil changes--few ever do!...you can tell when an engine has been cared for,and when one was neglected..the only thing I might use non detergent in is a very old engine that I think may have been run on it "forever"--or in a transaxle or air compressor where no detergent is really needed,no combustion by products to contaminate it in those applications..(I prefer gear oil in trannys ,but some take ATF or motor oil now--I have substituted 90W in a few with no ill effects,but I wont reccomend others to follow my lead,in case it does end up being a "problem")...
 
Discussion starter · #15 ·
Tractor-Holic said:
When I was working in auto parts stores,the factory rep for Wolf's Head oil told me that "Non Detergent"oil made after the mid 60's had SOME detergent in it,just enough to satisfy the needs if engines being made in that era..

.up until then, oils were mostly straight weight, and had to be changed at every season to allow for cold starts--then multi-weight oils were introduced,and detergents added to keep engines cleaner inside...
He said since a lot of "clueless" people might buy ANY oil and dump it in a newer car,so the "non detergent"oils were modified, and a bit of detergent was added to them >just in case"..non detergent oils I see sold now have the lowest ratings as far as anti-wear and resistance to breaking down--one label I read said "NOT for use in any engine produced after 1932 !..had a rating of "SA" on the label...
(A customer brought 5 quarts of it to my friends shop when she wanted an oil change--he showed her the label and she said "eh--my dad says :eek:il is oil"--its all advertising hype!--just use it,my cars a "junk" anyway":rolleyes:)--so I can see why they put that disclaimer on the label,but whetherit will actually harm a newer engine remains to be seen!)..

I was also told most non-detergent oils were mineral based oil (and many still are)--versus todays oils being derived from petroleum or synthetics..he said mineral oils dont lubricate quite as good ,and can go "sour" after a long time..he reccomended flushing the crankcase well in any engine suspected of having used non detergent a long time and using a good multi-weight or SAE 30 detergent oil,and said he used diesel rated oils in all his vehicles and yard equipment...

Its nice when you can be sure an old tractor or engine had regilar maintainence and oil changes--few ever do!...you can tell when an engine has been cared for,and when one was neglected..the only thing I might use non detergent in is a very old engine that I think may have been run on it "forever"--or in a transaxle or air compressor where no detergent is really needed,no combustion by products to contaminate it in those applications..(I prefer gear oil in trannys ,but some take ATF or motor oil now--I have substituted 90W in a few with no ill effects,but I wont reccomend others to follow my lead,in case it does end up being a "problem")...
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Yeah Im really fortunate with this one. Probably one of the cleanest I've seen in Maine. You don't see many Twin cylinder Suburbans up here in Maine, Mostly just the old one lungers. I think I will have to special order some Rotella 30w. Unfortunatley the guy told me they don't sell Rotella 30w at wal-mart anymore:banghead3. But worst case scenario I'll just run Pennzoil 30w in it.
 
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Discussion starter · #17 ·
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#18 ·
Down here near Boston I see Rotella T and Delo 400 on sale for less than 12 bucks a gallon at places like Autozone,Bennys,and Walmart has it sometimes,but usually they have their "Tech 2000" store brand diesel oil in 3 gallon jugs in 15W-40 and SAE 30...its just as good for what we're using it in...but I find bulk is cheaper at the big rig store..if your not against having 5 gallons on hand..I've seen 5 gallon pails at Walmart here too,they even have gear oil and tractor hydraulic fluid in pails--but not a lot OF them on hand,usually just one or two...not as cheap as the truck store though..
 
#19 ·
I use Rotella 30wt oil in my tractors and equipment in spring-fall. In winter, I switch to 10w-30. I used to use full synthetic 10-30, but not any longer. The Mobil 1 finds its way out under pressure and I wind up with a misty oil mess. I never really get that in summer when using 30wt. So, I've now use a dino 10w-30 for winter and it works just great. The hydro uses full synthetic Mobil 1 10-40.
 
#20 ·
boomers_influence said:
club.
use a detergent oil only.
change it every 25 hours.
i use rotella T 30 wt. year around. ( mn. but a heated shop)
the NON detergent theory is about 50 years old.
thank you. boomer (the used onan engine parts guy)
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I agree fully.--73searstractor-opened up a can of worms didn't ya!!:biglaugh::biglaugh:
 
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