Log Splitter Opinions

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Jags

Moderate Moderator
Staff member
Aug 2, 2006
18,237
Northern IL
It has been claimed (but I am not sure if verified), that synthetic is simply too slippery to do a good job of breaking in (essentially wearing in) the piston, rings, valves, etc. With small engines the break in period is measured in hours (not miles like an auto). I have seen suggestions everywhere from 2 to 10 hours for the break in period.

Note - my suggestion of oil change was not based off of break in time, but for removing any potential contaminates from the machining process of the engine components.
 

SpaceBus

Minister of Fire
Nov 18, 2018
6,080
Downeast Maine
Pretty much every single performance engine manufacturer on this planet breaks in their engines with synthetic oil, as do most builders. There is no reason to go with conventional motor oil unless you just can't afford the synthetic. Rotella T6 5w-40 goes in every single engine I own and there probably isn't a better oil you could buy for the money. BMW and some of the exotic car makers get oil made to their spec and those *could* be better than T6 but it is unlikely.
 
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DodgyNomad

Minister of Fire
Dec 19, 2009
657
West Michigan
Why do you not recommend synthetic for this initial break in period?

It may be old thinking, but most small engine builders don't do start ups with synthetic, at least not the ones that I know. Nor do the race engine builders I know. To my knowledge, most small motors don't come new with synthetic either, not that I've seen. I have often read and heard that for the all important ring seating sequence, that necessary break in between the hard rings and the cylinder cross hatch bore area is better achieved with dino oil, vs. synthetic. I do add in engine oil supplement to my engines that contain zddp and moly, but most won't go through that step, it reduces cam wear and lifter scuffing, more important on high spring pressure performance and racing motors.

So, for good cylinder seal, less blow by, less oil contamination, more power, and longer life, use traditional oil for the first 10 hours vs. synthetic. I go even a bit longer, but I also change my oil more frequently than recommended during the break in period on my personal motors.

You only get one chance to break them in properly, so I go out of my way to do it to the best of my ability. I won't bore you with more details, but it makes a difference in the long run. Fact.

There's plenty of time to use synthetic oil over the lifetime of a motor. But, because you're going to hopefully be doing a couple of very short oil change intervals, the traditional oil you'll be using won't be wore out, just full of lots of small metal particles.
 

DodgyNomad

Minister of Fire
Dec 19, 2009
657
West Michigan
Pretty much every single performance engine manufacturer on this planet breaks in their engines with synthetic oil, as do most builders. There is no reason to go with conventional motor oil unless you just can't afford the synthetic. Rotella T6 5w-40 goes in every single engine I own and there probably isn't a better oil you could buy for the money. BMW and some of the exotic car makers get oil made to their spec and those *could* be better than T6 but it is unlikely.

I didn't read your post before posting my reply a few minutes ago, but I respectfully disagree. When I google Engine break in, the very first link I see from Summit racing mentions the oil. I've heard this and seen it for years. I didn't search this out, or look for other articles, just the first thing that popped up, and I buy a lot of parts from Summit.



You can do what you want, but I can tell you from first hand experience that one of the best engine builders in our area, who currently owns many NHRA, IHRA, NMCA, etc., class records still uses non synthetic oil for all his break ins, with engine oil supplements for cam/lifter run in. I won't share what brand of oil and supplements he uses, but it's not synthetic. Just saw him do it a few weeks ago. Runs them only a few minutes, then drains, and refills, primes, and runs again. Guy builds motors for a living. No synthetic for a long time in any of his motors. Neither do the other engine builders that I personally know.
 

Bad LP

Minister of Fire
Nov 28, 2014
1,658
Northern Maine
I didn't read your post before posting my reply a few minutes ago, but I respectfully disagree. When I google Engine break in, the very first link I see from Summit racing mentions the oil. I've heard this and seen it for years. I didn't search this out, or look for other articles, just the first thing that popped up, and I buy a lot of parts from Summit.



You can do what you want, but I can tell you from first hand experience that one of the best engine builders in our area, who currently owns many NHRA, IHRA, NMCA, etc., class records still uses non synthetic oil for all his break ins, with engine oil supplements for cam/lifter run in. I won't share what brand of oil and supplements he uses, but it's not synthetic. Just saw him do it a few weeks ago. Runs them only a few minutes, then drains, and refills, primes, and runs again. Guy builds motors for a living. No synthetic for a long time in any of his motors. Neither do the other engine builders that I personally know.
I've built a few GM small blocks over the years and had a totally insane 700 triple triple that I built in a snowmobile. The SB's were easy with the oil because you just drain it. The sled needed the synthetic oil pumped out of the tank for break in.
 
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SpaceBus

Minister of Fire
Nov 18, 2018
6,080
Downeast Maine
Do whatever you please, but I personally know engine builders and unless you are building a flat tappet cam engine, synthetic all the way. Over the road trucks and the top tier racing classes all use synthetic oil, for break in and hard running. Formula One engines have to be filled up with hot oil or they won't even start, still synthetic. Current F1 rules dictate a small number of engine replacements, so synthetic oil is even more important.

There are of course examples that run counter to what I've said, but they are almost all antique or flat tappet cam/lifter setup. In these examples I would still break in with synthetic, but I would spec one that has lots of zinc or add some in.

Ever watch NHRA top fuel guys build an engine? They don't even use torque specs because the engine only has to make one or two 1,000 ft passes. The crew just slams the parts together with air tools and they could probably use vegetable oil and get away with it.

I spent a lot of time during some very boring parts of my military career reading oil sample reports and Bob is the Oil Guy forums.
 
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DodgyNomad

Minister of Fire
Dec 19, 2009
657
West Michigan
Do whatever you please, but I personally know engine builders and unless you are building a flat tappet cam engine, synthetic all the way. Over the road trucks and the top tier racing classes all use synthetic oil, for break in and hard running. Formula One engines have to be filled up with hot oil or they won't even start, still synthetic. Current F1 rules dictate a small number of engine replacements, so synthetic oil is even more important.

There are of course examples that run counter to what I've said, but they are almost all antique or flat tappet cam/lifter setup. In these examples I would still break in with synthetic, but I would spec one that has lots of zinc or add some in.

Ever watch NHRA top fuel guys build an engine? They don't even use torque specs because the engine only has to make one or two 1,000 ft passes. The crew just slams the parts together with air tools and they could probably use vegetable oil and get away with it.

I spent a lot of time during some very boring parts of my military career reading oil sample reports and Bob is the Oil Guy forums.

I'm one of the early and original BITOG members, with a 3 digit member number, so I dig where you're coming from. Oil debates and arguments have raged online since forever. I knew I'd end up regretting posting oil suggestions on here, as these threads always sadly seem to devolve in this manner no matter what forum it's on.

I certainly have watched quite a few Top Fuel motors get tore down and assembled, up close and personal while standing inside the trailers and behind the ropes, I've even assisted when a couple of teams were short handed at Indy, Martin, and Chicago.

I will continue to break in stock 4 stroke motors using what I've seen and learned until I'm proven that doing it some other way is better. I broke in 6 new motors in just the past couple of months, and they'll all get synthetic eventually, just not during the initial break in.

I'm not surprised and have heard of many builds and applications where utilizing synthetics is the way to go for break in, but don't believe this is one of them.

But for this application that we were discussing on a little log splitter, I'll have to see a lot more proof of why synthetics are better initially before I change what I'm doing for stock, low RPM, air cooled 4 cycles.

And, it's cheaper, so that's cool with me too when I'm dumping it out after only a short bit of time too.
 

walhondingnashua

Feeling the Heat
Jul 23, 2016
390
ohio
Ok so let me try this scenario... before all of these posts, I did start breaking the engine in, but because I'm going to dump it out, I used some O'Rileys (sp) cheap 10w-30 and have about an hour in on it. I have been running it at different speeds for random times, working my way up to full throttle (and splitting a little). I let it cool down as I change the throttle periodically.
What if I switched over to conventional oil for a few hours too? Continued to change the throttle and keep letting it get hot and cold. Could I potentially get the best of both worlds here?
 

DodgyNomad

Minister of Fire
Dec 19, 2009
657
West Michigan
Ok so let me try this scenario... before all of these posts, I did start breaking the engine in, but because I'm going to dump it out, I used some O'Rileys (sp) cheap 10w-30 and have about an hour in on it. I have been running it at different speeds for random times, working my way up to full throttle (and splitting a little). I let it cool down as I change the throttle periodically.
What if I switched over to conventional oil for a few hours too? Continued to change the throttle and keep letting it get hot and cold. Could I potentially get the best of both worlds here?

You'll be good. Not sure you'll get the best of both worlds, but draining the contaminated first startup oil, giving the motor a little warmup before running to WOT, and varying the RPM vs. running at the same speed continually when brand new and changing out the break in oil early on in the engines life vs. leaving it in for years and years as some folks do will have you covered.

I'm not sure I understand exactly what oils you've run up to this point, but todays modern oils are so much better than they were decades ago, that you really see very few oil related failures on these kind of applications, unless the oil is just way off on viscosity, or has super high hours, or contaminated.

We're kind of gilding the lily a little worrying about oils on these little motors to such a great extent.

One other thought because it's so cold here in Michigan, I try to pre-heat motors a bit before break in start ups by putting them closer to the heat source in my shop, and even putting a couple of space heaters near the motor to get them pre-warmed. If you think about the thermals of starting up and breaking in a motor that's ice cold, probably not the best scenario considering all the different types of metals used in construction, etc.

Where I think these warm up techniques are most important is on applications like little gensets that don't have throttles. The moment you start them, they're spinning up to 3600 RPM's. On a brand new engine, if it's 20 degrees outside, you're not doing things any favor by doing your break in on an ice cold engine.

Just more food for thought. But the oil thing is probably being over emphasized on that little splitter. All the modern oils will do the job. Just splitting hairs a bit.
 
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Grizzerbear

Minister of Fire
Feb 12, 2019
1,026
SW Missoura
I'm no expert mechanic that's for sure but one thing I do know is they last a lot longer with any kind of oil than no oil at all ;). I just pulled the trigger on a new splitter so I will definitely be taking the advice listed here on break ins.
 
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Jeff S

Feeling the Heat
Aug 31, 2008
344
Kimball,Michigan
Are we still talking about a log splitter that has a Briggs&Stratton engine that uses 10W30 oil ? Pick your favorite oil, change it once a year, split wood for years to come.
 

walhondingnashua

Feeling the Heat
Jul 23, 2016
390
ohio
UPDATE: Got a few hours and maybe a cord and 1/2 through it. About to change the oil. It has been working great and has split anything I have asked it to. Very happy so far.
 
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DodgyNomad

Minister of Fire
Dec 19, 2009
657
West Michigan
A quick update regarding engine break in. I'm rebuilding a Generac 15,000 watt generator with a 30 horse V-twin horizontal shaft air cooled motor.

While looking up the final torque specs for assembly in the factory service manual, I noticed a section on oil. In there it states specifically that after the initial break-in, it is "then acceptable" to use synthetic oil if you prefer.

But the factory oil is not synthetic on this model, and only after break in does generac consider synthetic oil to be an acceptable option.
 

Bad LP

Minister of Fire
Nov 28, 2014
1,658
Northern Maine
A quick update regarding engine break in. I'm rebuilding a Generac 15,000 watt generator with a 30 horse V-twin horizontal shaft air cooled motor.

While looking up the final torque specs for assembly in the factory service manual, I noticed a section on oil. In there it states specifically that after the initial break-in, it is "then acceptable" to use synthetic oil if you prefer.

But the factory oil is not synthetic on this model, and only after break in does generac consider synthetic oil to be an acceptable option.
How many hours on it? I have a spare engine for mine but my fear is the electric side pukes before the engine does and the new Kohler units are all electronic now.
Why they couldn't leave well enough alone has me scratching my head.
 

DodgyNomad

Minister of Fire
Dec 19, 2009
657
West Michigan
How many hours on it? I have a spare engine for mine but my fear is the electric side pukes before the engine does and the new Kohler units are all electronic now.
Why they couldn't leave well enough alone has me scratching my head.

I couldn't tell you the hours, sadly this model didn't come with a factory hour meter. My guess would be somewhere between 1500 and 2500.

I've installed a combination tach and hour meter on the unit to keep track of it for maintenance from here on out.