Why straight-weight 30?

[cfromc]

I have a Toro push lawnmower 5HP that spec's out as the "best" weight an SAE 30. Why does some lawn equipment spec out a straight weight instead of a 5W/10W-30? Wouldn't the multi-grade produce less wear on start-up yet provide similar operating temp thickness? Or, does the multi-grade shear out more/faster than the straight-weight and the manufacturers want to make sure that the oil stays in grade longer since the engine is air cooled? I use 5w30 synthetic but in the future I think I may mix 50% of that and 50% SAE 30.

Please chime in to let me know if I'm on the right track or if I'm way off base.

 

[80caprice]

What brand engine? Most are beginning to spec synthetic and the old straight 30 now.... yes you may get more consumption out of multi weight conventional (being its air cooled, it runs alot hotter) vs a straight weight....

5w30 synthetic is all you need, skip the mixing with straight 30.

 

[cfromc]

It's a B&S motor and the mower was in sad shape when I got it. I bought my house in March '04 and needed a mower so I picked it up from a house a few blocks away for $60. The self-propelling mechanism didn't work, 2 cables were broken and the oil was nasty. i replaced the cables, cleaned and refilled the "differential", replaced the belt and used it all summer and just added some Amsoil 5w30 as needed. The next year I changed the oil to Amsoil 5w30. Now this year i changed the oil again with Amsoil 5w30. I didn't use any oil last year or this year but it did use some the first year. I'm not having a problem with consumption but I just want to make sure I'm not damaging the motor. Even though it was only $60, I don't want to have to search for another one. If some of the new mowers are spec'ing 5w30 than I shouldn't have any problems. It will probably last forever. I only put about 30 hours a year on it.

 

[H2GURU]

I just bought a new Toro and their pamphelet stated use 30W oil, however, the B & S insert gave a temp. range type chart that POINTS to a synthetic 10w30 oil. As Toro's engine suppliers vary from model to model, the 30W recommendation is probabaly carried over wording that is used as an a$$ cover.

 

[mtgrs737]

It's more of a temp. thing I think. If you will be starting the engine in temps below 40 degrees then I'd look at the 5w30 or 10w30 to get things flowing faster. If you only use the engine in above 40 degree weather then the old standby 30w would be my choice, just remember that the small engines have no filter so change it often.

 

[labman]

But we have always run straight ND 30 weight. Of course, when I was a kid that was all we had, and we ran it is everything all summer. Cars and other stuff braving the winter got 20 weight until spring. They also died earlier too. My 02 Cavalier gets regular renewals of its 5w30, and I am not even thinking about replacing it.

When multi grade oils and detergent oils came out, they were more expensive and not that much benefit to a lawn mower. The typical mower only runs in warm weather and only 1-2 cold starts a week. Too many of them never have an oil change. So a shear and sludge susceptible 5w30 may not be as good for them as for my Cavalier.

There was a thread here earlier this summer, suggesting dumping the factory fill early. Could be a good idea, replacing it with a modern oil you don't have hunt around and buy special for the mower, paying a low volume premium for an inferior product. Might even make starting the mower easier. And yes, change it once in a while.

 

[LarryL]

30W is cheap, and how are you ever going to compare the wear you get with that of a better quality oil. If you see a service shop using 30W oil then the message is clear, they are cheap. You can make a judgment call that they may use other cheap stuff, too, filters gaskets, repair kits and this may reflect on the quality of their work. There is nothing about a 30W oil that would make it better than an API cert 5w30 oil. It is possible that the 5w30 might reduce wear during start and warm up, but how would you ever know. That's what the service guys know, too and they save a few buck here and there. Lawn mowers are a bit like cars in that the engine will probably outlast everything else with just a little care. In the end, use anything you like. I use left over Red Line 5w30 and have no idea what the difference will ever be with my Honda commercial lawn mower. I also put a fuel filter on the line and spray down and clean the mower after every use. I also clean the foam part of the two part air cleaner every time I mow my half acre. I would not run straight weight oil if it were free. And one final note, an ir gauge showed a 20F drop in temp on a new mower between the 30W the dealer sent me home with and the Red Line I now use. This was not actual oil temp but the crankcase, unpainted after a half hour of operation. After 6 months of use the mower starts up from cold on the first third to half of the pull on the rope. I have no idea what that proves.

 

[Jim]

Most mowers do not have oil pumps, so the cold flow properties are a mute point. It is more important that the oil that is in the bearing does not shear down. The oil there does not get replaced often as in a engine with an oil pump. A good straight weight will work just as well as expensive synthetic. The up side is that you can replace it often to remove the fuel contamination that air cooled engine have problems with.

 

[LarryL]

My Honda uses the cam drive as an oil pump and I wonder if the esters in Red Line stick better and transfer heat from the engine to the oil better.

 

[1999nick]

Do not forget that, for the last several years, Briggs & Stratton have recommended the use of synthetic oil in their engines, and sell a 5W30 synthetic under their own brand name.

I, personally, have one of those HONDA 5.5 hp ohc engines on my mower, purchased back in 2000, and used between 60 and 70 hours a year. I have used Mobil 1 5W30 exclusively in it since changing out the 30W that came with it at the 5 hour mark. I change once a year, and the engine has never used any oil in a 60+ hour OCI.

I use this mower year round, cleaning up leaves, etc., during the winter months. It gets used during temperature extremes from 32 degrees to 98 degrees, no problem. I usually change the oil in March, and the present change has been in for over 30 hours, and still no usage.

In the cold months, it starts easily, much easier than a straight 30W or a heavier multigrade such as a 15W40 as some on this board use. This means a lot to me, since I am 70, with a pair of arthritic shoulders. The thinner oils probably get much better distribution also with the oil slinger that most of the simple lower horsepower engines use. Better power and fuel economy also, since that slinger does not have to wade through thicker oil.

 

[gizzsdad]

I also have a Toro w/B&S engine. Used SAE 30 until reading here and on B&S website that 10w30 syn. was OK. I'm using Mobil 1 Extended Performance 10w30.

My issue is that I seem to be burning more since switching. Am very anal about checking before every use, and only needed to add a smidge about every third mowing before.

Now I have to add the smidge every time. It takes about 20 oz. to fill, and I've now used almost the entire quart adding smidges all summer.

 

[cfromc]

Wow, I haven't used any this summer at that was 5w30.

 

[LargeCarMan]

Sheer stable, NO VI improvers, what else can you say?

 

[toocrazy2yoo]

Hmmm...Wonder if a mower could use a good 5W20 with a dose of VSOT to thicken it a little, and give it a little moly and zinc?

 

[cfromc]

I don't know about that, remember, they are air-cooled with about a 2 mph "wind" as you push them. Its gotta get pretty hot.

 

[Brons2]

Quote:

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I also have a Toro w/B&S engine. Used SAE 30 until reading here and on B&S website that 10w30 syn. was OK. I'm using Mobil 1 Extended Performance 10w30.

My issue is that I seem to be burning more since switching. Am very anal about checking before every use, and only needed to add a smidge about every third mowing before.

Now I have to add the smidge every time. It takes about 20 oz. to fill, and I've now used almost the entire quart adding smidges all summer.

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My 6HP Briggs on my Snapper always burned straight 30wt, 5w30, 10w30, whatever. I'd have to top it off a couple of times a summer.

Switched to a 5w40 HDEO, Mobil 1 Truck and SUV, no more consumption. Starts really easily too even when it's down in the 40s.

 

[RMartin631]

Quote:

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I don't know about that, remember, they are air-cooled with about a 2 mph "wind" as you push them. Its gotta get pretty hot.

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There's a fan built into the flywheel of most aircooled engines that moves the air a good bit faster than 2 MPH. That's why it important to keep the screen on the recoil starter free of debris.

 

[80caprice]

Not only the screen....., the fan fins and cylinder fins....
And yes, it does kick it out faster then 2mph.... especially the newer engines with redesigned fans..