Grey oil in mower? (pic)

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Hi all,

I've been lurking for a couple of weeks - looking forward to being a member of this community!

As a housewarming gift, my grandfather gave me his Craftsman mower - the 37719 walk-behind with the Eager/Tecumseh 6.75 hp engine. To my knowledge, the unit's probably five seasons old. Other than blowing a ball of smoke during startup, the unit seems to run well.

Let me say that although my grandfather is my idol and as a man I've modeled myself after him, I think he may not be much for mower maintenance.

He changed the oil at the beginning of this season with some kind of 30-wt oil. Changed the air filter too. As the oil was pretty dirty after around 7 hours, I changed it again with Havoline 30wt. Drained it again after 1.5 hours, and the oil looked like this...

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After 1.5 hours!

What's giving the oil this color? It's not sludgy at all, just opaque, close to the color of pencil graphite. Am I still flushing out wear metals? Did I get water in the carb when I washed the mower?

Any help with this mystery is much appreciated. TIA,

miker
 
I'd place a drop between my fingers and rub them together.
If you feel any kind of grit or abrasive, I'd change again pronto.
You might look on the bottom of the mower and see if it has an actual drain plug. If so, prop the mower up on ramps or?? and use it. I feel you'll get a much better drain that way, compared to tilting the mower on its side.

You'll probably have to do a few more frequent changes to get most of the existing crud removed.
I'd just use the cheapest$ 30 weight detergent oil and change immediately after each mowing until things clear up.
The oil will probably always get "dirty" before its time to some extent unless the crankcase is thoroughly flushed/cleaned. That's probably really not worth the effort, considering the number of engines out there that last many years with NO oil changes.
 
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MikeR, I think you are still flushing out old wear metals ... as you have already guessed. The dirtiest oil I've ever seen has come out of old lawn & garden equipment.
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It looks like the oil was never changed ... and unfortunately that's pretty common with things like push mowers. Bogatyr was left in charge of his Dad's house many years ago when he moved away for a job and with the home came an old push mower. Same deal. Oil was an opaque grey color. Never changed in its life. He was speaking with his Dad on the phone one evening and mentioned that he had changed the oil in the mower. "What'd you do that for?" was the response.

I think it's the case more often than not.
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It also doesn't help that a lot of old timers believe you need to run a non-detergent oils in Briggs & Stratton engines. Sludge city.
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It is my theory that very short duration oil changes (with a modern oil) are very good for gently flushing out old crankcases. The additive package is fresh and best able to clean up residue left from previous oils.

So, I'd change it twice each year from now until the oil begins to stay clean. It probably only takes .5 - .6 of a quart. Then cut back to changing it just once in the fall.

--- Bror Jace
 
Looks like a very dirty engine and the gas was leaded fuel.

Run it until hot with new dino 30 weight HD oil and use 1 oz. of LC with each oil charge.

Repeat until clean.
 
I just overhauled my B&S with new rings and ground the valves. I ran the engine for about an hour then drained the oil and my oil had that same look. It has got me wondering if I put it together right; sure hope so. Do you think the gray black color has to do with the aluminum parts like rod bearings and the case working in.

Anyway I have a new fill of 30W oil in it with a little LC and will try it for another hour.
 
quote:

Originally posted by White 03:
I just overhauled my B&S with new rings and ground the valves. I ran the engine for about an hour then drained the oil and my oil had that same look. It has got me wondering if I put it together right; sure hope so. Do you think the gray black color has to do with the aluminum parts like rod bearings and the case working in.

Anyway I have a new fill of 30W oil in it with a little LC and will try it for another hour.


If it's an aluminum bore, you'll get a LOT of wear metals from your new steel rings scraping the high spots of the cylinder. It's akin to a knife edge cutting the aluminum!
If it is an AL bore, don't expect tremendous life from the engine. They just don't seem to last very long the "second time around". I guess it has to do with a coating?? on the original bore??
 
quote:

Originally posted by MikeR:
...Craftsman mower - the 37719 walk-behind with the Eager/Tecumseh 6.75 hp engine. To my knowledge, the unit's probably five seasons old. Other than blowing a ball of smoke during startup, the unit seems to run well.

Hmm, I have had the exact same mower for about 4-5 years, and the oil looked exactly the same as it does in your picture after I drained it the first couple times.
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I used 30w for the first change, leftover 10w30 for the second change (didn't leave it in long...was trying to flush that "glitter" out!), and 30w ever since. I've probably done a total of 6 or 7 changes on the mower. It took about 4 changes for that "glitter" to disappear completely. Runs smooth and starts on the first pull, so I guess it doesn't mean anything in terms of durability.
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[ May 13, 2004, 12:05 PM: Message edited by: RL ]
 
quote:

It has got me wondering if I put it together right; sure hope so. Do you think the gray black color has to do with the aluminum parts like rod bearings and the case working in.

Yep. Lot's of aluminum can also cause a "lead-like-look" to the oil.
 
I have a 6 HP B&S and the oil looks just like that if I use a straight 30 weight. I bought this mower new 3 years ago.

This year, I switched to Pennzoil LL 15W-40 (I know it's not recommended by B&S), but after 10 or so mows, the oil still looks good! (after 1 mow on 30W, it was already gray) The engine also runs better through thick grass. I haven't noticed any consumption, and it's getting pretty warm here!

My guess is that with no oil filter, I just needed a stronger ad pack?

Brian
 
Bill, mine is the IC model which I think has the cast iron cylinder so I am hoping for the best.

I ran mine another 45 minutes and drained the oil with the same results. I don't know if this would be MikeR's problem but I think mine could be cumbustion blow by from the new rings needing to seat. The oil has that kind of color, not a sludge look but more of a dark gray. A lot of glitter also but I suppose that is to be expected.
 
This year, I switched from the B&S brand SAE 30 to M1 10w30 in my 5.5 horse B&S. When I drained the oil oil, I could still see some of the golden color (this is from having run all season last year). Despite that, I wanted a full synth in there. The M1 is doing great. There is no consumption and it is holding it's color after 5 - 6 mowings (2 - 3 hours use). The engine does sound a little noisier, though, but not enough to worry me.

Having said this, it it was me, I'd try to get a look inside the sump to find out how much dirt or residue was inside. If it looks dirty, you might want to remove the motor, take off the bottom and do some careful cleaning, then see what happens to the oil. If the sump is already clean, you may need to check out different oil brands to see which works the best. Perhaps a good diesel oil could clean things up as well, as the other poster recommended, or maybe a flush with Marvel Mystery Oil.
 
I just found my golden purchase for $10, a Craftsman 5HP front tine rotortiller used once about 20 years ago had similar colored oil. the paint on the drain bolt was never scratched from a wrench. My fiancee overzealous after getting it fixed for $50 (carb clean/new fuel pump diaphrapm) used it to break ground/rotortill a 20x40 garden prior to checking oil. It starts better with the GC I dumped in. I imagine the engine life is compromised, should I put a cleaning product through or is it not worth for something you use a total of 2hrs/year (until your friend's find you own one!).

thanks
 
My latest lawn mower has a 5.5 hp Honda engine. It is not the heavy duty Honda engine used in their commercial grade mowers, and I understand it is rated for about 250 hours of use. Since break-in, I have used Mobil 1 5W30 oil in it, changed once a year. I use the 5W30 because I use this mower about 11 months a year, cleaning up leaves in the fall and winter.

I change this Mobil 1 once a year, usually in November or December. I use this mower a little over 100 hours a year. It has yet, in 3 years, to require any additional oil to be added. The oil stays a very golden color, darkening very slightly at the end of the year. I know Mobil 1 is expensive lawnmower oil, but two quarts lasts me 3 years.
 
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