Synthetic oil fouling plugs?

[Twin Pinzies]

This past spring, I decided to try Amsoil 20W50 synthetic. I have been very happy with the way they have been running until recently. They start easier and seem to run smoother. The one thing that I did notice was that the oil became very dark, very quickly. Now I am noticing that my plugs are increasingly becoming black and sooty while my other truck is starting to burn oil (never did before). Could this have to do with the Amsoil? I am almost ready to go back to standard oil. What do you guys/gals think???

[Kirby]

I would think there is a good chance that is your problem.
No problem before...... and now there is a problem. I would at least change back and give it some time to correct itself. If it corrects, problem solved.


And of course....let us know.

[75pinz]

I would think the synthetic oil is cleaning up deposits in the crankcase which is turning the oil black quickly. However, I would be that is not the issue with your plugs. Black and sooty typically means too rich mixture. (carburetion) As far as the other truck burning oil, I think most Pinz's do to some extent. I have had a lot of trucks (15) and most of them would use a quart between oil changes and would smoke upon start up. (valve seals) I use 15W40 conventional. (Delo or Delvac) This has been a pretty good selection for me without the high cost of synthetics.

[Twin Pinzies]

OK. So if it's running too rich, how do I "lean it out" a bit? I just had the carbs rebuilt but it did the same thing before the rebuild. It was fine for months. Now it will start stumbling (as if running on 3 cyl.) after two rides, usually following a long downhill (with engine breaking) will induce it to start stumbling. The only thing that fixes it is to pull the plugs and clean them. Then it will run fine for a few trips again.
How do I fix this?

[pinzinator]

Maybe the plugs you are running aren't hot enough? Jim posted an NGK recommendation a while back, they work fine in my 710. Do a search and get the part number and give it a try.

[Twin Pinzies]

Maybe the plugs you are running aren't hot enough? Jim posted an NGK recommendation a while back, they work fine in my 710. Do a search and get the part number and give it a try.

I am running the NGK's already....

[Twin Pinzies]

OK so I'm pretty sure that the synthetic oil is cleaning the sludge and deposits out from the inside of the crankcase. My question now is this... Do I change it back to conventional or "ride it out" with synthetic and hope that it doesn't start burning oil and sprouting leaks?

[Twin Pinzies]

OK, so here is the latest. Both of my trucks (with synthetic engine oil) have gotten progressively worse over the summer to the point where they were having trouble just idling on their own!... and have been leaking/burning oil more and more. I changed back to conventional oil/filter in both and guess what?... They ran great all of a sudden!! The synthetic (Amsoil 20W50) "cleaned" the gaskets/sludge/deposits to the point where the oil was jet black, thin, and ruined. The engine seals seem to be either incompatible with synth. or the engine tolerances are too wide, or both. These trucks get all new fluids and filters every couple of months since they are commercial tour trucks so I guess it's nice that they like the CHEAP stuff!

[Kirby]

Posted: Fri Aug 29, 2008 9:56 am Post subject: I would..
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I would think there is a good chance that is your problem.
No problem before...... and now there is a problem. I would at least change back and give it some time to correct itself. If it corrects, problem solved.
And of course....let us know.

WOW ~ I was right . . . . I am NOT rubbing it in, just happy that my suggestion was the one that worked! (Although there are lots of Great folks on here and great suggestions)
So how many ah $hits does that wipe out?

[75pinz]

I don't really see how it can be related to the oil really. Good luck anyway as Pinz ownership can often be a challenge

[Twin Pinzies]

I spoke to the Amsoil tech guy today and told him my story. He said that indeed what I had done was "flush" the crankcase by breaking down the petroleum distillates and carbon deposits present from 30 years of single grade SAE-30 oil. He said that I could tough it out with another "flush" cycle and hope for the best with the puffing smoke and the gaskets/seals or swap back. I decided that conventional oil is better for my Pinzies... since multi-grade conventional oil didn't even exist in 1974... say nothing about 100% synthetic!