Did Synthetic Oil Kill a Suzuki DR-Z400SM (Super Motard)

OK, been riding over 50 years, studied more about oil for motorcycles than I can remember and I thought the "synth oil can harm some engines" myth had been put to death. BUT, a guy I know who said his Suzuki 400 single, supermoto engine "blew up", according to his mechanic, because he switched to Motul's best synth oil and he should only run non-synth. My friend is a very smart guy and has been riding/wrenching for a couple decades himself but believes the mechanic. Don't know the year of the bike or what "blew" in the engine but says the mechanic was adamant that the synth oil caused it and he won't believe anything else. I call BS, what say the wise forum members?

 

has the wrench been doing mechanics for 30 years?

 

Ha, good question. The friend was a little lacking in info such as, what does he know about the mechanic and what exactly went wrong with the engine but that's all I got.

 

I'd find a new mechanic.

 

Good advice.

 

ask your friend if he volunteered the type of oil to the wrench. Theres a real easy way to tell for less than $35.

 

Yeah, unfortunately it happened a couple years ago so no oil specimens available.

 

Of course it blew up. That low-revving, under-powered lump designed for light-duty street/trail riding could barely contain itself when subjected to the high-revving, most likely power-modded use as a racing machine. It became too high strung from the ease at which it rotated and reciprocated when fed the ultra-slick oil.
So, yeah, it was the oil.
<edit> Oops. Sorry. Tech forum...no shenanigans. My bad.

 

Ha ha. Well, now that makes perfect sense. Just too slick.

 

I bet it was fast tho'! Just like a two-stroke, right up until the point it holes a piston.

In the case of what was likely sustained high rpm operation in a four-stroke, I'd go with ignition problem. With high rpm valve float, possibly to the point of a shim displacing itself, a valve could have hit the piston, got bent and didn't fully seat. The spark plug couldn't fire the air/fuel mixture 'cause there wasn't any. Never mind the new dome configuration and other damage that may have preceded the ignition problem.

I can't readily see any other explanation. Could have been lack of maintenance on the valves, too. A quality oil would have had zip to do with it.

Of course, unless you see the damage, there's no telling what really happened.

 

I'm afraid we'll never know. I'm just trying to talk some sense into my friend but maybe he'll never believe it was anything but the oil.

 

Or maybe it was the BNG?

 

Depends is the oil fill hole on the right or left side of the engine?

 

They musta been really bad but, for sure, graphics can kill a bike. No doubt.

 

It has. This thread is cringey.

 

You could run that engine on mineral oil and it would last a while so something else is going on besides the oil

 

Ah, she was a pretty good old whore, too.