Lawnmower tractor oil question

[sh00ter]

I have a lawn tractor w/ Chinese single piston motor. Sticker on the motor that says 10w30, but the manual allows for a different range of viscosities to be used based on climate. I've been using Rotella 15w40 T5 because this is a flat tappet motor and at the time I bought the jug, I was aware it contained a decent amount of ZDDP and phosphorus and is also a syn-blen which I prefer. On my latest oil change I didn't have enough left in the jug to fill it, so I wound up having to use about 50% Mobil-1 15w50 (SN-rated) to make up the difference.

I know mixing oils is fine because I have done plenty of research on oil in the past, but my concern is the dilution of the ZDDP by adding the SN-rated oil into the blend. If I recall, the Mobil-1 15w50 still contained a decent amount of anti-wear additives since a lot of folks use that oil in boats and race cars? I am sure this tractor motor has relatively weak valve springs, so I would not think it will matter, but I wanted to get opinions on whether its okay to run this fill for the next 50hrs, or if I should drain it in favor of something that is formulated for sure for flat tappet motors.

Historically, I always liked to use straight 30wt oil in generators, mowers, etc. But the 30wt oils available locally are all conventional and I like to run a syn-blend or full-syn if I can.

Okay, I've over complicated this enough, let's hear the opinions.

 

[sh00ter]

Well I may have found my answer...even the newest SP-rated Mobil-1 15w50 is 1100PPM on ZDDP!!! The bottles I had were unopened but several years old so being the previous rating (SN), they probably have at least as much or more as the SP version, so I think I'm good?

 

[swampratt]

I got rid of my 302 ford van in 2013 and I ran all kinds of motor oil for testing MPG in that one and some did not have 1000 PPM and it never hurt a cam or lifter.
But like yours weak valve springs.
Stock used 60 PSI on the seat and under 200 open with a 260H comp cam grind.

 

[sh00ter]

I got rid of my 302 ford van in 2013 and I ran all kinds of motor oil for testing MPG in that one and some did not have 1000 PPM and it never hurt a cam or lifter.
But like yours weak valve springs.
Stock used 60 PSI on the seat and under 200 open with a 260H comp cam grind.

I was taking bets in my head if you would be the first reply LOL!

I was in a pinch and needed to get the service done; otherwise I would have just gone and bought some more of the same oil. But after seeing this, I might just switch over permanently since I already stock the 15w50 for other things anyway.

 

[sh00ter]

@swampratt

 

[swampratt]

VR1 is what my 57 chevy and my 47 Dodge get.
Been using it for decades and good to hear they improved it.
I never had any issues with it before and sounds like that will hold true for many more years.

 

[Raido Free America]

I have a lawn tractor w/ Chinese single piston motor. Sticker on the motor that says 10w30, but the manual allows for a different range of viscosities to be used based on climate. I've been using Rotella 15w40 T5 because this is a flat tappet motor and at the time I bought the jug, I was aware it contained a decent amount of ZDDP and phosphorus and is also a syn-blen which I prefer. On my latest oil change I didn't have enough left in the jug to fill it, so I wound up having to use about 50% Mobil-1 15w50 (SN-rated) to make up the difference.

I know mixing oils is fine because I have done plenty of research on oil in the past, but my concern is the dilution of the ZDDP by adding the SN-rated oil into the blend. If I recall, the Mobil-1 15w50 still contained a decent amount of anti-wear additives since a lot of folks use that oil in boats and race cars? I am sure this tractor motor has relatively weak valve springs, so I would not think it will matter, but I wanted to get opinions on whether its okay to run this fill for the next 50hrs, or if I should drain it in favor of something that is formulated for sure for flat tappet motors.

Historically, I always liked to use straight 30wt oil in generators, mowers, etc. But the 30wt oils available locally are all conventional and I like to run a syn-blend or full-syn if I can.

Okay, I've over complicated this enough, let's hear the opinions.

I retired from Sun Refinery, over 20 years ago. I didn't work in the lube oil section, but learned a few things about it's operation. I understand they canned about 116 different brands of motor oil, from Texaco, John Deere, Penzoil, Ford, GM, Castoil, etc. just about every brand you can name. There are only two or three GRADES ( API STANDARDS) of oil, and all these were canned using one of these 2 or 3 grades of oil, the only differtence is each brand has their own additives, the same is true of gasoline,and diesel fuel! Synthetic oil came along after I retired, and I don't know anything about that?