Maurices Exotic Pets

Slow Engine Flush

So you just purchased a high mileage truck with questionable maintenance and you want to get it as clean on the inside as the outside, here is how you can reduce the risk of causing damage to your engine.

Let’s get to the nitty gritty about engine flush products out on the market today; many are all solvent in nature. They are designed to free up oil sludge and clean varnish when mixed with your regular oil at the time you do an oilchange, a few are designed to run in the crank case while the vehicle is inuse.

Engine deposits are by nature abrasive, when you add a solvent to your oil the deposits are broken free and become suspended in the oil. The oil now has less film strength and more abrasives than ever before. Ina no or low load situation abrasive particles are filtered out by the oil filter up to a point where the filter media is unable to flow due to excessive loading of particles and the bypass valve opens. Unfiltered abrasive laden oil then rapidly accelerates wear on critical engine components.

How fast can this wear happen? At an idle speed of 650rpm you are looking at 9550 engine rotations in just 15 minutes, that’s a lot even with a mild abrasive.

So we want to avoid the abrasive oil being circulated into the engine if at all possible, so how can we do this? Short oil change intervals with filter changes at every oil change help reduce the possibility of your filter becoming clogged and going into bypass mode. Newer oils made with more and better detergents slowly remove deposits and allow the deposits to accumulate in the filter, very short oil change intervals are used to prevent these freed up deposits from getting to the point of clogging the filter.

The following method is designed to minimize the risk of damage to your engine and should provide you with outstanding results over the span of 6000 miles, after which you can go with a regular maintenance schedule that suits your vehicle usage.

With the engine at operating temperature; drain the oil, and change out the filter with a primed low cost filter of your choice, replace thedrain plug and add an appropriate quantity of low cost oil, drive the truck easy for 20-30 miles, immediately change the oil and filter for an oil that contains high levels of detergent and a quality filter, drive the vehicle as you normally would for the next 1500 miles.

You will repeat the above at each 1500 mile interval a totalof at least four times, checking your oil for any rapid change in color at every fill up. If you notice a rapid change in color this is an indication that the filter is in bypass mode and is full of abrasive particles, regardless of mileage repeat the above steps as soon as possible.

I suggest reserving a small sample of your old oil to monitor progress, glass baby food jars are fine for this, just mark them with the mileage and put them on a shelf. Your 1500 mile oil samples will obviously look more contaminated than the 20-30 mile samples but you should see an improvement over the span of four changes in all of the samples.

When is the slow flush done? Your slow flush is done when you aren’t seeing an improvement in oil contamination levels, meaning the oil you are using has done all it can do to remove deposits and sludge. You may decide to continue the process with a different brand of oil if you wish, the steps will be the same.

If you decide to follow the Slow Flush with a rapid flush I suggest the following method.

With the engine at operating temperature; drain the oil, and change out the filter with a primed low cost filter of your choice, replace the drain plug and add an appropriate quantity of low cost oil minus the quantity of engine flush used as directed on the products label, run the engine at idle for the minimum time recommended by the flush product, immediately drain the oil, and change out the filter with a primed low cost filter of your choice a second time, drive the truck easy for 20-30 miles, then once again change the oil and filter for an oil that contains high levels of detergent and a quality filter, drive the vehicle as you normally would and change your oil and filter at an appropriate interval for the use the engine sees.

The above method takes into consideration that used oil and filters are already contaminated with abrasives and have less lubricating potential than new clean oil. An additional consideration is given to completely removing the chemical engine flush prior to normal use of the vehicle.

The above recommendations are primarily intended for people who have come into ownership of vehicles with questionable past maintenance and a desire to start their own maintenance off as fresh as possible. The slow flush portion is generally safe by any way you define the term, the addition of the follow on rapid flush is designed to be less risky than it would be if done alone and by any other method.

Flushing of any kind does not fix major engine damage or wear, what it does do is stops additional damage caused by slow flowing oil through gummed up oil galleries and allows some measure of personal satisfaction that future maintenance is not being contaminated by past neglect.

Visual checking of any oil samples you hold on to is not a replacement for lab oil analysis; it is just a layman’s way of judging how your progress is going.

If your vehicle is throwing codes, address those issues, the flushing methods addressed above are not likely going to correct those faults.

I’m just another car guy, not your mechanic, and certainly not wealthy, if the methods I described above result in your vehicle blowing up you’re not going to get a whole lot out of me, so use your own judgment if you feel the methods are suspect.

Maurice

DIY

High detergent lubricating oils have their own faults including excessive camshaft and lifter wear, and excessive oil changes can produce just as much wear as infrequent oil changes.
For example: Back in the 1980's a close friend who thought he was "pampering" his 1983 Honda Prelude managed to destroy the camshaft and cam followers in only 12,000 miles with too frequent oil changes every 750 - 1000 miles, using top grade products. The Honda tech told him the oil never had a chance to "break in" and the constant renewal of oil maintained a film of excessive thickness, causing excessive wear.
Replacing the oil filter when it is operating in bypass mode is sound advice, but if the filter is operating normally, hold off replacement until after performing a quick flush. It will save a few dollars and not hurt the engine. Most low cost oil filters trap any particles larger than 40 - 50 microns. Premium oil filters trap particles as small as 30 - 40 microns.
To perform a quick flush, the oil level should be 1 quart low on the dip stick. If the oil level indicates full, warm-up the engine to operating temperature, then remove the sump plug and drain 1 qt. of oil. Reinstall the drain plug and immediately add 1 qt of #2 diesel fuel to top up the engine's oil level. and run the engine at idle for a minimum of 3 minutes and no more than 5 minutes, while continuously monitoring the oil pressure from your instrument panel's oil pressure gauge. Then perform a normal oil and oil filter change using oil that meets the manufactures specifications.
Follow the manufacture's recommended oil change intervals and preform a quick flush every 3 or 4 oil changes, but only if you avoid using higher detergent "high mileage" engine oil.
Synthetic, synthetic-blend and high mileage oils do not require a quick flush if the recommended oil change interval is followed.
Oil filter replacement is the subject of much debate. If your budget can afford it, change the filter every time you change the oil. Otherwise, remove and drain the oil in the filter and reinstall the same filter per manufacturer's instructions. Check for leaks after a test drive, ensuring proper oil pressure is maintained and replace the oil filter every second oil change.

Maurices Exotic Pets

Doing a quick engine flush on an engine with an unknown quantity of abrasive contaminants is a risky operation, if the level of contaminants exceeds the holding capacity of your filter rapid wear will happen, this even applies if you notice no drop in oil pressure that might indicate a clogged oil passage.

Oils job is to float parts on a film of oil, and to suspend contaminants in a circulating river of oil that ultimately flows through the oil filter who's job is to prevent those contaminants from remaining in the circulating oil.

Oil filters have a fixed capacity of contaminants they can carry and still flow enough oil to meet the engines needs without going into bypass mode, this is when a filter has met its maximum filtration life.

If the filter has not met its contaminant holding capacity, one must still recognize that the oil it is carrying over at an oil change is diluted with fuel, and acid, as well as potentially devoid of any detergents or other additives to its base stock. While maybe just a 1/10 of the total oil capacity it does reduce the oils quality right from the start.

No excessively short oil change interval has ever caused rapid wear, conversely they may prolong engine break in time (that also is the topic of another post). The fact remains that oil is not abrasive, and its mode of operation within an engine is to float parts that would otherwise be in direct contact. Synthetic oils get to the parts and do this job just as well as conventional oils, and have the additional ability to remain stable under a far wider range of conditions. The fact that the base oils are so good that they have room to add more effective detergents is nothing more than a secondary gain.

Your advice on quick flushes using #2 diesel fuel is not sound advice for the situation I described that is suitable for doing a slow flush. On an engine with unknown maintenance intervals and potentially high levels of sludge, it is unsafe to rapidly dislodge huge heavily contaminated globs of what amounts to polishing compound into the oil stream knowing very well that no oil filter could possibly hold enough of those contaminants to prevent rapid wear even in the very few minutes you describe.

My method is safe and effective, never did I mention economy in the text, it should go without saying that maintaining an older vehicle is almost always more economical than buying new, not always but almost always.

As for cost; premium oils that will stay in the vehicle run around $30 for 5qt jugs, the low buck flush out oil I use runs $12 for a 5qt jug. Filters, two per oil change total about $12. Total cost out of pocket for me to put a known high quality oil in the engine is very similar to having a quick lube shop put in their synthetic stuff out of a 55gal drum and a house brand filter.

In my experience once an engine is healthy and regularly maintained flushing at any interval is not required, and nothing more than a waste of time and money. But you have to get there first.

Maurice

DIY

Purchasing any used vehicle is a risky proposition, Maurice.
As for my input about flushing the engine every 3rd of 4th oil change, it was common practice back in the day when non-detergent oil was the norm and not the exception. In fact, some of those early L-head and other configurations of flat tappet, flat-head engines built prior to 1954 should continue using non-detergent oil, but oil change periods should be much shorter due to the formation of sludge and varnish that is normal with non-detergent oil.
My point is this; if there is excessive sludge in the oil-ways, main oil galleys, and in the bottom of the oil pan, it is a sure bet some of the piston rings are probably stuck and the rod and main bearings are worn "down to the copper", that is until a few years ago when the bearing makers began substituting zinc alloy backing materials for the more expensive copper backing.
I had also noted in my previous post, how often to change the oil filter is a much debated subject.
It is not just regular maintenance that is at issue here.
Stop and go driving coupled with short trips is considered severe service, just as driving long distances over dusty gravel roads like those in New Mexico and throughout the Midwestern states is considered severe service, requiring more frequent oil and filter changes, or the life of the vehicle will suffer.