Straight 30 or 15W40 for hard use air cooled small engine?
- Thread starter z71bill
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I wonder if the engines are getting low on oil and the small amount of oil is getting too contaminated to lube properly?
I went with the HPL 5w40 CK4 cold climate so it’s got an HDEO add pack, a PAO base oil, and the typical HPL top treat of all the good stuff!
Both my generator and pressure washer call for 30 grades but Dave mentioned there’s not a much better/safer way to approach these small engines than with a good 5w40.
I had an hd40 straight weight left over that I ran as topoff oil in the oil burner OPE.
In my personal experience over the last 10 years or so, I'm just not happy with T6 5w40 in any of my small engines or motorcycles. It's consumed faster and it shears faster than the 15w40's and noticeably less smoother running. It is a darn fine oil and I use it in my Ram EcoDiesel, but no more in small engines or motorcycles.
Not sure this has been brought up yet, but I converted a Honda 390 to a carb that will accept NatGas and Propane. Honda's instructions are very strict, that if you convert to NatGas, you must run a straight 30wt. So that genset is running T1 Rotella 30wt. It's been running great and that dang engine is probably going to last 20 years.
This thread is very timely for me, as I just purchased a small piece of farm equipment that has the B&S 13.5hp 420cc engine... the XR variety that boasts 3x more engine life. I am wondering what oil to use, as the manual calls for a 30wt, but I also read about the small engine failures with 30wt oil and am thinking I will only use HDEO 15w40.... most likely SuperTech and change it very regularly.
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Not sure this has been brought up yet, but I converted a Honda 390 to a carb that will accept NatGas and Propane. Honda's instructions are very strict, that if you convert to NatGas, you must run a straight 30wt. So that genset is running T1 Rotella 30wt. It's been running great and that dang engine is probably going to last 20 years.
This thread is very timely for me, as I just purchased a small piece of farm equipment that has the B&S 13.5hp 420cc engine... the XR variety that boasts 3x more engine life. I am wondering what oil to use, as the manual calls for a 30wt, but I also read about the small engine failures with 30wt oil and am thinking I will only use HDEO 15w40.... most likely SuperTech and change it very regularly.
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Hmm, what engines are you noticing more consumption in with a 5w40? The most noticeable difference in consumption for me is only in worn out engines, or when using a PCMO 5w30 vs a HDEO. If I use a HDEO 10w30 it still works great with no noticeably consumption UNLESS... it is in something old, something with a ton of hours, or something used commercially.
Let's start with my 6hp Honda on my push lawnmower. That engine is tight and solid. I change the oil in it annually. The first two years I used RT6 5w40 in it and I would have to top it off as Fall rolled around. The next year I changed to RT4 15w40 and it was still full as winter fell upon me. The last two summers I have run SuperTech HDEO 15w40 in the mower and had the same results as the RT4.
Then we could move to a new Suzuki Vstrom DL650. On a 1,400 mile ride, it drank nearly a quart of RT6. I tried several oils after that, but eventually landed on RT4 15w40 and the consumption nearly stopped.
Look, I love a great synthetic when the application is right for it, but I also love a great conventional when the application is right for it.
Interesting story.......
So I have a close friend that was a salesman for a commercial lubrication company. Some of his largest clients are in the Oil and Gas industry. Some of those big pumpjacks are powered by a generator that is fed natural gas for fuel. They run 24/7, 365... unless they break down. They have some type of mechanism in the engines that keeps the motor oil topped off in the sump. The oil is never changed in these engines, they are continually topped off. They are fed a diet of straight 30 wt conventional. I asked him once if they ever considered running a synthetic... and he said no way. He said they would consume synthetics much faster.
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That's a good data point. Any weak points on Generac units from your experience?
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Might have to try 15w40 in my 1969 JD 140 H3 garden tractor. The single cylinder Kohler works hard on a 46" deck, and it consumes a bit of oil, from full to low every 5 to 10 hours in the heat of summer. This is with Rotella t4 10w30. Thanks for the info!
Bot did I go down the rabbit hole on this thread!
I have a Champion 8750w Portable generator, currently it has Kirkland Synthetic 5W-30 in it, for no other reason than my F150, Big generator and mower are also running 5W-30 (Well, apart from when I put 5W-20 in by accident) so I can stock a single weight of oil and use it everything
The book says recommended 10W-30, but 5W-30 Synthetic is on the chart. I am in Houston, TX.
The generator is stored in my detached garage which should never get below freezing during a winter storm (If it drops below freezing, I will heat it)
The generator is a backup to my Generac RG027-QS, and could be used during a hurricane or possibly another winter storm. Seems to me that 5W-30 is a good oil choice, but after reading this thread I am not so sure.
The generator would not be loaded to max for extended runtimes, and it does have an eco mode to lower the RPM.
Should I maybe switch to 10W-40? Or 5W-40? Any other suggestions welcome
I have a Champion 8750w Portable generator, currently it has Kirkland Synthetic 5W-30 in it, for no other reason than my F150, Big generator and mower are also running 5W-30 (Well, apart from when I put 5W-20 in by accident) so I can stock a single weight of oil and use it everything
The book says recommended 10W-30, but 5W-30 Synthetic is on the chart. I am in Houston, TX.
The generator is stored in my detached garage which should never get below freezing during a winter storm (If it drops below freezing, I will heat it)
The generator is a backup to my Generac RG027-QS, and could be used during a hurricane or possibly another winter storm. Seems to me that 5W-30 is a good oil choice, but after reading this thread I am not so sure.
The generator would not be loaded to max for extended runtimes, and it does have an eco mode to lower the RPM.
Should I maybe switch to 10W-40? Or 5W-40? Any other suggestions welcome
Most all small, air cooled gas engines have a small oil capacity, no oil filter, are splash oiled, and run very hot. So thicker oil, along with more frequent oil changes are going to be required.
I have no complaints and no real consumption using whatever 0W-40 I buy at Walmart. I use it in my lawn mower, my garden tractor and my snowthrower. Lately it’s been that Amazon Basics 0W-40 we got a while back for dirt cheap.
Very interesting. I'll admit I haven't run T6 5w40 in a while due to it not being a good value anymore, but didn't notice consumption with it in the things I used it in. I mainly use Rotella T4 15w40, T5 10w30, Valvoline PB 10w30/15w40, and lately Delvac 15w40 with some Supertech 15w40 sprinkled in. I go through a lot of HDEO between all the machines I service for customers and my own/family equipment.
4WD
$50 site donor 2025
I have a year old 42” LT … they are not getting cheaper …
However, no worries running it on 6 year old PPE 0W40 that was $1/quart … The motor has a filter and lube flow … changed 2X year …
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The weakest point or issue by far is vibration, pull cord recoil , battery maintenance on the E versions and final the fuel filters getting plugged up in that order
I do check the valves every 300 ish and get to see inside
Still running 15w40 leftovers from 5 gallon buckets that fill 14 quart powestrokes
I agree with you. My go-to OPE oil when I lived in Florida was Mobil1 15w-50 and it served me well but after I moved to New England I had to rethink that. I still use the Mobil1 for my summer engines like mowers but I'm not thrilled with the T6 either and I'm on the hunt for something else.
I am also in Houston.
I will only use 5w30 even full synthetic if temp is below 40 degrees.
I am surprised the recommended oils does not include Straight 30.
I have a supply of B&S 30 and a bunch of 15w40.
I also scored some Valvoline blue in 10w30 semi synthetic on sale for $20 - gallon.
Has the Valvoline VR1 10W30 been changed recently? I saw it last night and instead of 2X more zinc in said 1.7X.Broke in my pressure washer with this. (first 50 hours) Now I have conventional castrol gtx 10w30 in it, mainly because that's what I had laying around.
I heard an interesting story today on a Old Kohler fb page. I mentioned that I use Rotella 15w40 in all of my air-cooled 4 cycle motors and a fellow responded with this: as I understand it, the disadvantage of multi-viscosity oils in these engines is that it breaks down quickly and before long your oil is all (or almost all) 15w.
I ask him his source and he replied: I believe it was from an old engine guy who had also been a college professor. Unfortunately he’s no longer with us. But he’d gotten the data from a reliable source. Possibly Kohler.
Now that was not good enough for me, it is sort of hearsay to me. I use the Rotella because it has zinc, which my old vintage engines need. And because when my brother worked for New Holland, they ran tests on this diesel rated oil and found it to be very good. I plan on contacting Shell and see what they say.
Thoughts?
I ask him his source and he replied: I believe it was from an old engine guy who had also been a college professor. Unfortunately he’s no longer with us. But he’d gotten the data from a reliable source. Possibly Kohler.
Now that was not good enough for me, it is sort of hearsay to me. I use the Rotella because it has zinc, which my old vintage engines need. And because when my brother worked for New Holland, they ran tests on this diesel rated oil and found it to be very good. I plan on contacting Shell and see what they say.
Thoughts?
that is a lot of shearing IMO to get a 15w40 down to a 15w15... I personally think it is a wives tale. FWIW, I have seen 5w40 shear down to 5w30 in my Cummins with Mobil Delvac ESP).
Just my $0.02
