5-W30 vs 10-W30 oil


Thanks for all the informative replies. As my dad often said, not all education comes out of a textbook. :grin:


@Marnet I don’t know how old your mower is, but it may have been manufactured before synthetic oils became available. I would either recommend following the manual and using straight 30 viscosity oil or using full synthetic 10W-30. I would not use 10W-30 that is not synthetic.
If you aren’t fogging for mosquitoes as you mow (i.e. your mower isn’t.puffimg blue smoke), it may be best to.stick with what your manual recommends.


The mower isn’t smoking any. I checked the oil at the beginning of the summer and it was full and clean. I’ve checked it twice since and it was still ok. Last mowing the motor began rattling a bit at the end. So the next day when the mower was cool I checked and found the oil is very dirty dark and down to the fill level on the dipstick. So time to change the oil.

I had it serviced once, per the manual schedule. But the cost to have it picked up, serviced, and returned has gotten very expensive. So I’m going to do it myself. Change the oil and air filter, and sharpen the blade. I may need help from a neighbor with getting the blade off and back on. I do have the rasp my dad always used sharpening mower blades.

Worst case, I holler for help from a neighbor or pony up the price for the lawnmower shop to service it.


You can just take the blade to a shop for sharpening and it will be balanced also.


Ah, didn’t think about the balance. Thank you for reminding me!


Air cooled engines get hotter than liquid cooled ones.

Multi grade oils used to degrade wirh the higher temps. the length of the molecules would decrease and the viscosity would drop and that is why the manufactures would specify 30 weight oil rather than 10W-30.

Each successive change in the letter grade of the oil has improved the oil and today’s SN oils are much more resistant to thermal breakdown which is why most small engines use multi-grade oils today.

My 1972 Airens was called a (2 wheel) tractor and could be had with various heads, a sno-thrower, lawn mower or a rototiller. They used multi grade oil with the sno-thrower and straight 30 for the summer attachments.

Spell check doesn’t like sno-thrower but that is the way Airens spelled it.


If its a Briggs, or other brands too, in the old days they said 30 wt. best in the summer or 10w30 ok. Then 5w30 in the winter for snow blowers. Now they say to use 5w30 synthetic year around. 30 weight straight is hard to come by so I use 5w30 synthetic in everything.


Balancing is easy and not technical. There’s a nifty little cone shaped device which you can buy from your shop or probably on Amazon for about $10. Or if you have a thin nail, drive it into anything like a wooden fence post, work bench, exposed stud in a shed or garage…make sure it’s parallel to the floor. Then, after you’ve sharpened the blade, pop the blade onto that nail using the hole in center of the blade. The side that drops lower is heavier, so file off a bit more and try again until it’s sort of close. No need to be fanatical about getting it perfect, “close” is good enough. And your “rasp” may be ok, but rasp usually means a file with big coarse teeth. You don’t want big teeth for filing metal, you want something fine. And maybe that’s just what your father used and called it a rasp.
BTW: bravo to you Marnet for doing this yourself! I’ll bet you could also change the oil in the mower, you’d just need a 3/8 drive ratchet and a short extension, might even find one of those at a thrift store. The drain plug on many mowers is just a 3/8" compatible plug underneath the deck. Make sure to remove the spark plug wire before tipping the mower on its side.


The hardware store isn’t really singing you out. They’re totally uninformed about a lot of things. ND and HD oil is probably their worst area of inexpertise. If your engine calls for any SAE 30 then you shouldn’t try a 5W30 or 10W30. I had to pick my own key blanks at one store because they couldn’t match SC1 to the SC1 that was right on the rack.

Back to the oil; they make non-detergent SAE 30 because it’s so thick that stuff stays in suspension for a long time and it kind of negates the need for detergent oil. Your engine might run forever on either one.


The rasp has a coarse side and a fine side. Dad used the fine side sharpening mower blades. But I don’t have a whet stone anymore for a final edge finishing. I don’t even know where to get one. No one seems to know what a whet stone is. I assumed I could get one from either the kitchenware or hunting supplies departments.

I may just wait until Monday and go to the lawnmower shop to get the air filter and while there ask about the blade sharpening and even which oil they use when servicing mowers.

I know how to sharpen blades having helped my dad with it a few times. The challenge will be getting the blade off and then securely tightened back on. I have fairly severe arthritis. But I also have some good neighbors with strong hands. :grin:

The user manual gives fairly good instructions with diagrams on all the maintenance items. My biggest challenge is lack of muscle strength. For example, I cannot safely handle even a small electric chainsaw. So I used a gardening coping saw to cut down four hugely overgrown yew shrubs a few years ago. Took me a few hours a day over a week’s time but I got it done!


WalMart sells straight 30 HD oil in their supertech brand. In my store, it is not shelved with the other motor oil but rather with the lawn mower supplies, still in the general auto area. I have been using it for years and my lawn mower engine is in fine shape. Sometimes I use a little 10-30, but only in the winter.


I also have a 58 volt EGO 21 inch mower, not self propelled version. I love it and I will likely never go back to gas mowers again. My only nit picking complaint is that when mowing tall weeds, the rear discharge chute sometimes clogs and then it reverts to a mulching mower. It also has a way to close the discharge chute for those who want a mulching mower. I have never used it as a bagging mower even though it is equipped with a grass bag.
It comes with a very fast battery charger, less than an hour. It forces cooling air through the battery while charging which allows for that fast charge.


3 acres on a charge.


I don’t think you need a whetstone for a lawnmower blade. If that’s how your dad did it, I think that means your rasp is too coarse, even on the fine side. His file may have been digging too deeply into the mower blade and all he had to correct that problem was the whetstone.

An ordinary cheap fine metal file is all you need, any hardware store or home center will have several choices. They’ll have a whetstone too.

The coarse side of your file suggests that this is a tool intended for wood, not metal, and that the “fine” side is still pretty rough. Just a hunch, reading between the lines of your posts. I have a tool that sounds like what you’ve described, and I’d never consider using the fine side for metal. Your lawnmower shop will be able to clarify when they see what you’ve got. It’s entirely possible that your dad had only one file, so used it for everything, and he may have gotten it from your grandfather!


I use my belt sander to sharpen lawn mower blades. Just make sure all the wood sawdust is out of it because metal sparks can set it on fire. (speaking from experience)


@WesternRoadtripper1 the file was from one of my great-grandfathers who was a blacksmith in his younger days. :grin:
Thank you for the advice.


Belt sander to sharpen a lawn mower blade . That sounds like an accident just waiting to happen .


I used to sharpen my blades on the grinder but now I just use the angle grinder with the grinding disk. Works fine. You don’t want a razor edge on a lawn mower blade because of the load cutting grass puts on it. Just follow the original angle and grind out the pits.

Edit: All I used to hold the blade is one of those large welding clamps, like an overgrown vice grip.


@Marnet. Some years back, I bought a tool which I think is called a mower blade breaker. It clamps to the deck of the mower and goes around the blade, locking the blade in place. With the mower blade held in place, I put a socket on the bolt holding the blade to the engine shaft. With a long enough handle on the ratchet , it doesn’t take much effort to loosen or tighten the bolt that holds the blade to the engine shaft. I have an electric grinder that I use to sharpen the blade. I dip the end of the blade being sharpened in water before and during the sharpening process to keep from drawing the temper out of the steel.
When I put the mower away for the season, I change the oil, put in a new air filter, sharpen the blade,fill.the gas tank with gasoline to which I have added stabilizer, remove the spark plug and squirt oil into the cylinder, turn the engine over a couple of times until I feel through the spark plug hole that both the intake and exhaust valves are closed, and screw the spark plug back in. At the beginning of the next season, I put in a new spark plug and pull the starter cord. I’ve never had the mower fail to start on either the first or second pull.
@B.L.E. I am glad you love your Ego mower. I find it hard to love any mower as I hate mowing. Mrs. Triedaq loves to mow, but has had two foot surgeries and two rotator cuff surgeries. I thought a self propelled mower would be just the ticket, but she didn’t like the self propelled feature when she used her dad’s mower. She likes the little 18" aluminium deck Toro that I bought back in 1988. I thought she would like the battery powered Black and Decker I bought from a friend. However, the lead acid batteries make it too heavy for her to push comfortably. The Ego mower you describe might just be the right mower. The lithium-ion battery would make it lighter and easier to push. She might just fall in love with the mower and I could get out of mowing. Then I would love the Ego mower as well.


I take the blade off the mower and I now use a bench belt/disk sander to do it.

It’s also handy for a lot of other things.
Mine is actually a Ryobi but it looks so similar to this that it may have been made by the same company.