Hello Iatn Folks,

In my day-to-day operations I work on a lot of older farm equipment and vehicles. A majority of them have been maintained well, but there is always some that have more than obviously suffered neglect or been sitting for many years unused.

Generally, it is not hard to tell the condition of the inside of an engine if the valve cover has been pulled off. If the top end looks clean inside that usually means the rest of the engine has been taken decent care of. (note); I never consider an oil fill cap with a little sludge in it to be a valid check for top end sludge. Why? Because it is a natural occurrence from the oil fil cap being a cooler (temperature) part. That "cap check" as seemed too always be a common sales pitch, even back when I was starting out years ago.

I started out in the 70's when it was common to use kerosene (in the oil) in a typical gas engine to help clean the internal oil sludge out of them. We would drop oil filter and empty it and reinstall it then add about a quart of kerosene to the remaining oil. After that we would run/drive the car at moderate speeds for about 30 minutes with the diluted mixture.

Once the run was finished, we would proceed with a conventional oil change and check all the other servicing then send the customer on their way. (Of course, grease fittings were common back then also. LOL)

As time went on though engine flushing service was gradually abandoned as all the new "cooler running" aluminum engine designs were coming out along with improved detergent oil blends. Engine sludge was practically eliminated.

It is rare that I perform an engine flush these days, except on old gasoline tractor projects or a vehicle that has had a questionable service history. As I alluded to before, if I have to replace a valve cover gasket due to a leak and I find the top end full of sludge, then I will suggest an engine flush as part of the repair process.

The cons of this process I have learned over the years is that when an engine flush is performed there is a likely chance of choking up the pickup screen. This taught me to pull the oil pans on practically every Dodge and Jeep model (80's & up) because they had very small pickup screens and typically in a depression formed into the oil pan where deposits would collect and build up. (Have to wonder what genius engineer came up with that idea). In these cases, I suggest you warn the customer before suggesting any kind of flush on any engine. Make sure they not only understand the benefits, but also the risk of more labor being involved if the pan has to come down for a thorough cleaning.

The pros I have to offer mainly address older gasoline engines. I have witnessed several "oil burners" suddenly clear up and quit using a lot of oil and along with that the mileage also improved. Of course, a new PCV valve is advised as part of the service. In the case of gas farm tractors, the engines would run smoother and have more power especially under load.

What are your opinions out there folks, about engine flushing? (I've also sadly heard it called wallet flushing quite a few times)

Glenn A. Hunt
Consultant/Owner
Automotive Doc's
Devine, Texas, USA