engine oil

[One Tough Pressure 580]

I have been having a stalling problem after the washer runs for several hours and my local dealer says that in the past they have found that the cause of this was either old oil, or improper type being used, causing the heated oil to get pushed into the cylinder and reducing or eliminating spark.

Anyone ever heard of this?

I use 10-30 with an SL code, and the book calls for a 10-30 with a SJ or higher. I was using Castrol and last round I used Quaker State. I will change it and see if the problem goes away.

[Pams Pressure & Clean 64]

Alan,

I question your shop guy.

I have heard of oil thinnning issues when the oil gets super hot, but oil should never get into the combustion chamber for any reason. If it does, it is a failure of the oil rings on the cylinder or a failure of the valve seats in the head and a rebuild is necessary. The amount of heat required to cause the oil to thin enough to bypass the cylinder rings would also accelerate engine wear to critical levels. This does not mean that oil doesn't change with heat.. it does. I just don't believe you have that much heat.

Further, it would take a very significant amount of oil to snuff out a spark. Not something slow, and you would notice massive amounts of oil smoke from the exhaust long before such a catastrophic event and you would notice that you are having to add oil regularly.

I might suspect a margianlly low oil level and/or a marginal oil pressure cutoff switch.

It could be that once the oil gets hot and starts to thin slightly your switch is losing contact and shutting down. Similarly, if the oil level is marginal, the same effect could occur.

I might suggest an oil change then monitor the oil level like a hawk.

FWIW, we run Slick 50 in all of our equipment and top off with Valvoline high mileage 10w30 motor oil. We have never had an oil related failure.

[Aplus 525]

Alan,

I've been using Mobile 1 10w30 with no problems. In the smaller engines, I've used it for the ten years I've been in business. On the All American, I switched to it after the rig had about 40 hours.

[beyoungsr 14]

Alan,

I also use 10w30 synthetic. We have been using it for about a year now. We have not had any problems with low oil conditions like shut downs ect since switching.

The slightly increased cost can be viewed as cheap insurance for the engines.

[Pams Pressure & Clean 64]

Alan,

Any updates?

[One Tough Pressure 580]

Ran the machine again for several hours with no problems. I had a feeling the oil story was a weird one.

I am leaning towards the stop diode on the magnetos, and next time it happens, I will pull the wires and see if it happens again.

These intermittent problems are a pain to diagnose.