30 wt oil or 15-40

[37chief]

I have plenty Shell 15-40. I use it in all my diesel motors. I am changing oil in my pressure washer with Honda GX390 13 hp engine. The manual says not to use multi grade oil, just 30 wt. So that is what I will do. Is there a reason not to use multi wt oil in this engine? Here is what happened to me 15 years ago. I used 15-40 oil in my Allis Chalmers 4 cyl. gasoline motor. It didn't take long for my motor to lose power. One piston seized. On a 60 year old motor I would think it has plenty of clearances. I cleaned up the piston, and wall. It has been fine since I switched to straight wt oil. I have no idea why the 15-40 oil did what it did. Any thoughts? Stan

 

[rustyfarmall]

Shell Rotella 15w-40 is what I use in my 1940 Farmall H and M. Works very good.

 

[Steve@Advance]

Hard to say if the multi grade caused the piston to seize.

Could have been a coincidence.

I run 15-40 in everything except the late model stuff that wants lighter oil. Haven't had a problem yet.

 

[VicS]

Don't think was changing oil that ruined your motor. I put 15x40 in my AC WD45 back in 1987 Still going strong. But I have moved on to 5x30 synthetic in all our new cars,trucks and small engines

 

[dpendzic]

I would stick with the manufacturers recommendations--muti weight oil has more additives---do you really need a winter grade oil in your location?

 

[Geo-TH,In]

Here is my take, the first number is for when it's cold.
New cars are requiring 5w20 or 5w30.
I want my first number to be 5 so on cold starts the oil flows faster through filter and Oil flows faster to lubricate engine.
Not sure if the 13 hp honda has a filter. I gave the 13 hp pressure to my boy. I've always used 10w30 or 10w40 in my mowers, tractors , pressure washers. Kaw mule calls for 10w40.

I have switch my generators over to 5w20 full synthetic. Easier to start if very cold weather. Use 10w30 full synthetic in my Ford Jubilee 20 hp Honda. It does have a filer.

The hydraulics on my old terramites called for 10w30 or 10w40. Newer terramites say you can use 15w40 in summer. As for me I recently changed hydraulic oil and used 5w30 synthetic blend. I like the way hydraulics work on cold start ups. Hydraulic shop told me oil gets hotter if it can't flow freely to the pump.

Use what the book calls. I would also say what some can use depends on their climate.

All my old GM cars and trucks call for 5w30 oil. New car calls 5w30 dexos and they claim it goes 6k on oil change.

So my personal preference is using 5w or 10w, not 15w oil in gassers.

Can't really say I've ever had an oil related engine problem. I'm pushing 70.

 

[MarkB_MI]

I seriously doubt the use of multi-grade oil per se trashed your AC. However, if you went from a non-detergent oil to one with high detergency, that could have caused some problems.

Are you looking at an actual Honda manual, or one from the power washer manufacturer? When I pull up the manual for a Honda GX390, it says:

"SAE 10W-30 is recommended for general use. Other viscosities shown in the chart may be used when the average temperature in your area is within the indicated range."

The chart shows it's OK to use straight 30 weight above 50 degrees F. Which, perhaps not coincidentally, is the temperature range in which you're likely to operate a power washer.
Honda GX390 manual

 

[oldproudvet]

I use 15/40 in all my old stuff (not synthetic). I use older Case tractors on my farm, and I want the thinner oil for start up (where almost all wear occurs) and the heavier oil for warmed up temps as the clearances are much different than newer engines. All the newer engines/eqpt/tractors/cars whatever use Mobil synthetic. My 1990 Ford F-350 pick up with a 460 gas engine and a 5spd has over 500,000 miles with the only engine work being 2 timing chains, it still uses no oil Mobil 1 since new. Your oil did not cause your Allis failure. It was ready. So many times seized and scuffed pistons are caused by excess carbon build up behind the upper compression ring leading to blow by where the combustion heat gets by the rings and burns off the lubricating oils...... Very common problem in older tractors with there very basic carbs that run a rich mixture when not working hard (pulling a disc or plow). Just my 2 bits. PS I also like Studebakers, that lets you know where I am........

 

[ErnieD]

Multi weight oil may be 30-40% viscosity modifiers; and in dino oil they cease working after 2,000 miles. Air cooled engines used to consume multi viscosity oil and smoke badly (in my experience). Switching to straight weight dino oil or Group IV synthetic fixed the problem.

 

[Crazy Horse]

ERNIED ...Dino oil .... as in Dinosaurs or maybe Dyno oil? You should let the oil manufacturer know this, they'll probably modify the formula based on your experience. Two thousand miles isn't very good.

 

[Determined]

(quoted from post at 18:56:43 09/30/18) Multi weight oil may be 30-40% viscosity modifiers; and in dino oil they cease working after 2,000 miles. Air cooled engines used to consume multi viscosity oil and smoke badly (in my experience). Switching to straight weight dino oil or Group IV synthetic fixed the problem.

Not sure of the chemistry or science behind it but every big block GM engine I have owned would tell you when it was due for an oil change.
Go say 5000 miles with out using a drop of oil then they will use a quart in a week, you can add more and a week later it will be low again.
Change the oil and you are good for another 5000.

Currently running Mobil 1 synthetic in my 8.1 and it does the same thing.

 

[ErnieD]

I use Dino oil to reference non group IV synthetic oil. Air cooled engines typically run hotter than water cooled, hence the accelerated break down. I pretty much exclusively use synthetic group IV oils. Oil is inexpensive compared to downtime and metal.
Oils are changing rapidly to accept the demands placed by direct gas injection, turbo/super chargers, and longer drain intervals. A saving grace has been fuel injection and tighter build tolerances.

 

[Texasmark1]

What's the published date of the manual If back in the late 50's, early '60's it's because multi viscosity oil wasn't perfected like it is today (was the story I got) and the 30 wasn't always 30 like it was with "Single G" (Gulfpride Select Single G, 30 wt). On a pressure washer used in the summer, why not 30 if you have it. To me it'd just be one more oil to stock.

 

[grizz02]

I know on motorcycles with wet clutches you need to run there oil because of the anti-foaming properties in it, I ran auto oil in a 1000cc Kawasaki and when it would get hot it would lose oil pressure,the oil was all foamed up, changed to motorcycle oil problem solved