If I had that engine, I wouldn't have any qualms about using 30, 10W-30 or 15W-40. I would base it on the temperatures I expect to encounter, most likely 10W-30 since we can have cool Springs.
I won't use 10W-40 for anything.

I would ask Bill...If you wouldn't use 10W40, why then,
15W40? A multi-viscosity oil as indicated by the "W" in
ANY oil, will be OK to use (10W30 or 5W30), BUT...as the
manual states, MORE OIL will be used in hot weather. For
"grass mowing" you'll NEVER GO WRONG using 30HD and making
oil changes per the suggested intervals. An engine can use
a good bit of oil in 25 hours, and CHECK IT EVERY TIME
before you mow. I change mine every 12-15 hours, or in
average/normal use, is about 4 times a season. Air filter
and FRESH gasoline is also a....MUST...in today's hotter
running emissions engines, no matter who makes it. Bottom
line....NEVER USE a 40 weight oil of ANY KIND in an air
cooled engine that's operating at 400+ degrees on a hot
summer day.

T-Man

I vote for 30 weight,The reason is, it will always be just that,30 weight oil ! (I only use 30 weight in the push mowers,that my customers bring in...) Jim

Check your manual - mine says 30W okay down to 32F. In any event, I see no point in second-guessing the engineers who designed the engine - use SAE 30HD. Castrol makes a very good SAE 30 along with Quaker State. If you want the convenience of pre-measured bottles, the 18-20 ounce bottles are widely available. Just one more thing - the low temperature range given is the temperature of the oil before starting, not the ambient air temperature, so if you keep the mower in a semi-heated attached garage at 50F for example, you would be safe with SAE 30 even if it were 30F outside. On the other hand, if the mower stays in an unheated shed and the overnight low was 32F or less, I wouldn't start it until it warms up. The key is making sure the oil is not too cold to flow properly at start-up. After starting, the oil quickly warms, as the oil is the primary coolant in an 'air-cooled' engine. I had a Honda with GCV and the book said 10W30 for all-season use, with 30W okay for temps over 50F. I elected to use 30W and not start the mower below 50F since I have a 2-cycle to run in cold weather if needed. The difference between the Honda and Tecumseh oil requirements are simply tolerances and engine design.

So 30 weight it is. Now how about trying to get a diesel 30 weight because of all the extra good stuff that comes with it?

"I would ask Bill...If you wouldn't use 10W40, why then,
15W40?"
We're talking dino here so-
A multi weight oil starts off as a base weight oil (10 for a 10W-40)and Viscosity Index Improvers (VII's) are added to get the "hot" rating.
The greater the spread between the cold & hot ratings, the more VII's are needed.
VII's DO NOT LUBRICATE! All they do is prevent the oil from thinning out as much when it's heated.
A quart of multi weight oil is about 75-80% "oil" and the rest is additives. A 10W-30 oil is around the 80% mark and a 10W-40 is around the 75% range. A certain amount of additives are things like anti wear agents, anti foaming agents and other "good" additives etc. The difference is the amount of VII's added.
Under severe conditions, VII's "shear". The greater the amount of them, the more shearing takes place.
VII's have improved over the years. That's one of the reasons you see newer cars specifying "thinner" oils like 5W-20 etc. and also the reason you now see 5W-30 common place. Even though they are better than they used to be, the still don't lubricate.
I've pretty much settled on 10W-30 for my 18+ year old Honda mower. It's easier starting in April with 10W-30 than 15W-40 or a straight 30.
IF I was mowing commercially, where I had ONE COLD start per day and mowed a lot of hours, I'd go to a straight 30. NO VII's!

You indicated 30w was recommended for temps over 40 degrees, so presumably there is also a recommded oil for temperatures below 40. I would just use the oil recommended by the manufacturer and and get back to worrying about cutting the lawn.

I'm sure your lawn repair guy means well, but his recommendation comes without a solid reason for doing so.

IMO the Diesel-rated oil is not required or desirable. If you want to spend some money on it, check out Opti-4 SAE 30 oil, about $6/20 ounces. It's what I use in my LV195, the Honda before that and a 3.5 HP B&S before that (bought in 1989 and still in use by a relative - no oil burning yet - I just went over it for her last week). I sold the Honda - nothing was wrong with it except it was limited to 3" height of cut. A commercial service bought it.

Here is a link that might be useful: Opti-4

as a test i am using mobil 1 15-50 in my new lv195 to see how long it lasts on synth oil

As a test, I am using Mobil 1 5W30 in my mower with the Honda 160 OHC engine. It was purchased in 2000 and gets used 60 to 65 hours a year. I change the oil once a year, and it has never used more than a 1/16th of an inch of oil in a year's time. It gets used year round, cleaning up leaves and other yard debris in the fall and winter. To keep track of how much it is used, I have an hour meter on it. It gets used in temperatures ranging from 32 to 98. Higher or lower, and I won't be outside doing yard work.

I am down to my last quart of old formula M1, and I am reluctant to use this new oil with the "SM" rating. I may have to get some of that Briggs & Stratton synthetic, which is not SM, or possibly some of that Amsoil 10W30/30 oil specially formulated for small engines. As you know the new "SM" oils are formulated to protect catalytic converters in automobiles by changing the antiwear additives.

i have a 91 honda 215 i bought new and have run only mobil 1 in it -its had severe commercial use its entire life and is still running strong. dosent even smoke or burn oil between anual changes. will be interesting to see how the techumche does on it. i wish some one wouyld make a straighth 30 w synth . 10-30 is too thin for florida heat.

saxman1, why would diesel grade not be desirable. My understanding is that there's more good stuff along the lines of anti friction additives than regular gasoline engine oil. Would I actually be hurting the little LV by using diesel grade?

The stuff I purchased (which I can always return) is a straight 30 weight, SAE CD, "designed for heavy duty industrial/commercial engines." The stuff is made by shell and sold under a house brand label.

sax man prefers to waist his money on opti 4 when any sae 30 w is just as good.opti 4 isnt even synthetic . for the $ you might as well use full synthetic and you get a full quart 32 oz vs 20 onces. opti 0il both 2 and 4 stroke are over priced and over rated. who in their right mind would run 100/1 in a 2 stroke?

"i wish some one wouyld make a straighth 30 w synth . 10-30 is too thin for florida heat."

Actually, if you compare a straight 30 dino and a synthetic 10W-30, I don't think you'd see much difference in viscosity when HOT. (Florida HOT)
Synthetics have similar viscosity characteristics to water (I said similar, NOT identical).
Hot or cold, the actual viscosity doesn't change too much.

Perhaps my use of Opti products is 'overkill', but I like to stick with what I know works. In the commercial lawn business, I agree that use of certain expensive products is not justified, but for the homeowner who changes oil once a year, the cost is not important. FWIW, I also use Opti-2, but at 66:1. It probably is okay at 100:1 but my nerve runs out at 66:1. It has been working for me at this ratio in Lawn-Boys and other 2-cycles for 13 years. Deposits are minimal and there is never a need for exhaust port or muffler cleaning. I recently sold my 1994 LB 10201, and the compression actually felt higher than new - the front wheels would come off the ground when pulling the starter cord. This is one of the major effects of Opti oils - surface improvement by 'Eutectic' means. It definitely is not synthetic, being a paraffin-based oil. Plus, Opti oils are designed for air-cooled equipment where automotive products are not.

the v series lawnboy has no compression relese mechanism. thats why the weels jump off the ground when pull starting. good you use opti 2 at 66/1 . wise choice. i used opti 2 for many years till it got too $ as i was using 5 gallons of mix fuel /oil a week back then. my entire 21 mower fleet was 2 cycle back then. i mixed at aprox 70/1 . i find mobil 1 2t to be the best 2 cycle oil yet and thats what i use today. amazing stuff. at 7$ per quart it makes 12 gallons of mix at 50/1 . its actually cheaper than using opti 2 and better oil .

I put a drop of Marvel Mystery Oil with the provided oil SAE 30 Bottle inside the engine. The engine is brand new and I have to change in 2 hours of running.

Was I wrong by putting MMO with the Oil?

Or It will give me no benefits?

Should I change the oil right now?

Thanks,

intravino

Briggs & Stratton recommend and sell under their own brand name, a synthetic 5W30 oil, and say it is their 1st choice for temperatures between -20 degrees and +120 degrees. They say that using regular multigade oils will cause increased consumption when temperatures are above 80 degrees. They recommend their synthetic oil for use in all small air cooled engines.

You will be okay using MMO in the oil up to one ounce to 20 ounces of oil. You can replace this ounce every five hours or so of operation since it will be used up (the solvents will burn off). Do not overfill the crankcase.

Thanks Saxman for your quick reply:

Intravino

Intravino,

ANY "new engine" WILL CONSUME oil during its break-in
period, which usually is in the first 3-5 hours of use.
Many engine folks recommend changing the oil at 5 hours
to insure the break-in period is successful. Also, a new
engine will sometimes have a slight aluminum trace color
in the oil after the first few hours. Bits of aluminum
flashing from the manufacturing process can also be worked
out during the break-in period, and changing the oil early
on gets these impurities out of the crankcase. Oil is CHEAP
(or...it USED TO BE), and fresh gas, clean oil, and a clean
air filter will translate into....LONG ENGINE LIFE !!!

T-Man

People like to get all worked up over this or that oil,
which is fine.
10w40 oil is an engine killer though, it breaks down into a molasses type goo. The bottom bearing can seize,
even though there is plenty of oil in the mower, the odor of the broken down oil is hard to forget.
When, and if you can get the engine apart, the black tar is stuck to everything, soaking in gas is the only way to clean it. Many use the oil religously, with no problems
or so they think. Engine problems in the past were probably blamed elsewhere.
Otherwise, good clean oil is the key, miracle products or oil are not needed, only if they make you feel better.
Clean oil and air filters are the key for long engine life,
you will replace the mower for other reasons, normally.

Fish

'the v series lawnboy has no compression relese mechanism. thats why the weels jump off the ground when pull starting'

I thought it was clear in my post that the compression had INCREASED over the years. In fact, it got so high (by feel) that I thought something had to be wrong, but it wasn't. This is the result of using Opti-2 which actively works to mate moving parts, providing the minimum blow-by in the cylinder. BTW, which Lawn-Boy 2-cycle has any kind of compression release for starting?