Stay conventional or go full synthetic?

[97 AZ LC]

This theory that synthetic oil is so clean that it causes leaks is certainly widespread on the internet. Does anyone have any support for it?

 

[cmassa]

I'm on my 3rd oil change using synthetic. I first used M1 synthetic and an oem filter at 195K miles. I ran that for 5000 miles then changed with M1 Extended Life synthetic with a M1 209A filter. Changed that at 12000 miles because I had towed a trailer for 2100 hard miles. Just changed out for the same thing and plan to go 15000 miles.

That's a big benefit of synthetic oil - longer service interval. And the cost is not that much different anymore. I buy the 5 quart bottles online from Walmart.

Running great and no leaks. Currently at 212K miles on my LC.

Chris

 

[CloudCity]

This theory that synthetic oil is so clean that it causes leaks is certainly widespread on the internet. Does anyone have any support for it?

My statements were based on actual experiences, but from the classic car world, not specific to these rigs. I've always had classics and have spoken with many folks who have switched to sythnetic and then experienced leaks, for the reason described above in the thread. The most recent event was last summer when a friend w a vintage Benz like mine switched his fuel injector pump to synthetic oil and it almost immediately started leaking after the first couple of drives. Those are very costly units to rebuild and reseal so it was a several thousand dollar job, whereas if he kept the conventional in place he would have likely had no problems. Keep in mind these tend to be cars from the 60's through 80's so that could be a factor as well. Our Cruiser/LX seals may not be as degraded and maybe why folks seem to be having good luck using synthetics. I'm simply risk-adverse.

 

[97 AZ LC]

My statements were based on actual experiences, but from the classic car world, not specific to these rigs. I've always had classics and have spoken with many folks who have switched to sythnetic and then experienced leaks, for the reason described above in the thread. The most recent event was last summer when a friend w a vintage Benz like mine switched his fuel injector pump to synthetic oil and it almost immediately started leaking after the first couple of drives. Those are very costly units to rebuild and reseal so it was a several thousand dollar job, whereas if he kept the conventional in place he would have likely had no problems. Keep in mind these tend to be cars from the 60's through 80's so that could be a factor as well. Our Cruiser/LX seals may not be as degraded and maybe why folks seem to be having good luck using synthetics. I'm simply risk-adverse.

I wasn't questioning that synthetic oil has a tendency to leak, but rather this relatively recent theory that synthetics cause leaks merely because they clean so well. "It cleans up all the gunk that was holding in the oil" - smells to me like an internet "fact" - something that somebody made up and then a million people repeated it because they liked the sound of it. I was just wondering if there's anything of substance behind it.