Engine Flush?

[Mark S.]

I have a '67 w/a 427 and I'm considering flushing the engine. Has anyone ever flushed their engines with these machines they use at the oil change businesses? My first reaction is that it would be good to get the garbage out of the engine but I want to know if anyone else has tried this and did you have a good or bad experience? All comments are appreciated.

Thanks,
Mark (member #34132)

[Mike McKown]

Re: Engine Flush?

I guess I would have to ask, if your coolant is not a dirty brown color or something else, why would you bother to flush?

Mike

[Mark S.]

Re: Engine Flush?

Hi Mike,

I just thought that with an old engine it might be good to make sure the lubrication channels are all cleared out. It's not somehting that I have to do, or even necessarily need to do, but just something I thought might be worthwhile to help keep an old engine running even longer. I'm not in a rush & after I posted my question I thought that it might not even be possible since the mid-years have those silly canister oil filters.

Mark

[Duke W.]

Re: Engine Flush?

Don't waste your money on an "engine flush", but do start using 15W-40 heavy duty diesel engine oil (API service category CI-4). The major national brands are Chevron Delo, Shell Rotella, and Mobil Delvac.

Assuming you drive your car only a few hundred to a few thousand miles per year change the oil and filter annually, and if you store the car during the winter, do the oil and filter change just before storage.

Duke

[Mike Yager]

Re: Engine Flush?

I have read that using the oil engine flush is only necessary if oil changes have been neglected on an engine over a period of time. If the oil is changed on a regular basis, it is not needed.

About four years ago I needed to leave one of our cars in at the dealer for some warranty work. Since the car was also due for an oil change, my wife went ahead and told them to change the oil while they were working on the car. I went to pick up the car and was hit with a bill for $100 for an oil change. They had done the engine flush as part of it without asking. The service clerk tried to tell me it was needed even though she could not explain what it was. After having a conversation with the service manager, I ended up paying for a standard oil change. With the exception of someone who has neglected to change their oil as needed, I suspect some shops may be pushing this onto people that do not need it as a way to boost profits on low margin business such as oil changes.

I don't use this dealer any longer.

[Eric Fairclough]

Re: Engine Flush?

I know that some dealers drain the ioil and fill it up with transmission fluid and idile it for 10 minutes and then change to oil and they say this is the best way to get all the dirt out. I never tried this personally though. Eric

[John Lokay]

Re: Engine Flush?

Duke,
I assume that the 15-40w heavy duty diesel oil will provide adequate protection for my L-72 when driving during the hot summer months? In the past, I have used 20-50w Quaker State in the summer and changed over to a 10-40w in the winter (I live on Long Island; hot summers and cold winters) Also, I assume that the diesel oil does not break down like non-diesel oil and therefore your recommendation to change the oil only once per year. John

[Mike McKown]

Re: Engine Flush?

Sorry Mark. I had radiator flush on the brain. I went to an instant oil change place for the first time in my life about three months ago. On the wall was a list of scheduled services and one of them was an Engine Flush for many dollars. I don't remember the amount but I had to inquire what it was they were selling. I did not want their service on the flush but I left there thinking this was another way to gouge the public.

Nasty stuff inside of engines is not nearly as common today as it was before crankcase ventilation systems and detergent oils. I have torn down engines with 150,000 miles plus that did not have anything more than a "smear" of sludge in casting pockets. Then again, you will run across one that is heavily sludged before it needs an overhaul.

Adding a quart of transmission oil or a quart of Casite will help clean out deposits. Might even help sticky rings and lifters. There are some, including me that recommend that if you have a sludged engine, the best thing to do is let it alone and not try to knock all that crap loose. At worst, you might knock something loose you don't want to and at the least, all that stuff will be circulating through the bearings.

[Duke W.]

Re: Engine Flush?

If you look at your '66 owners manual, you will probably find that 10W-30 is adequate for any ambient temp. above about zero F, and straight SAE 30 is suitable for all ambient temps. above 40 F.

A 15W-40 should be more than adequate for ambient temps. from about 10F to whatever you will experience on the high end for anything short of road racing. For road racing an oil cooler would be a definite MUST!

The oil change interval in your owner's manual is also probably speced at 6000 miles or six months. Given the higher quality of oils of today and absense of daily cold starts, an annual oil change is sufficient for vehicles that see low mileage accumulation, and most OEMs now specify an oil change at one year if the mileage limit had not been attained.

The commonly available CI-4 oils are mineral oil based, so they will oxidize at about the same rate as a mineral oil based SL oil, but, again, if you drive no more than 3000-5000 miles per year oxidation will not be an issue. Synthetic base CI-4 oils are available. As with synthetic base SL oils, their primary advantage is lower oxidation rate, so if you don't accumulate a lot of miles you're not getting anything for the additional expense.

As I always say, the primary criteria used to select a motor oil should be the additive package, not the base stock oil, and CI-4 oils have a higher concentration of detergent, dispersant, anti-wear, and anti corrosion additives, which will provide better long term protection for our vintange engines that tend to generate more harmful combustion byproducts due to their imprecise fuel control relative to a modern emission controlled EFI engine. The richer additive package of CI-4 oils will better handle the acids and other corrosive combustion byproducts that slowly build up in the crankcase and their higher concentration of anti-wear addtives will reduce cold start and warm up wear that accounts for about 80 percent of total engine wear over the life of a typical automobile engine.

Duke

[John H.]

Re: Engine Flush?

GM issued a TSB to all their dealers about four months ago advising them NOT to use that (aftermarket) "engine flush" equipment on any cars, as it is likely to cause latent engine damage and its use will void the powertrain warranty.

[Eric Fairclough]

Re: Engine Flush?

This was actually a foreign car tech.

[Dave Suesz]

Great results with pre-change cleaner...

Since I got my first car, decades ago, I have always run Gunk engine flush through the crankcase just before changing the oil. My vindication for this was when I tore down the engine in my driver after approx 200,000 miles, and the walls of the block inside had a film of oil on them, and no sludge at all. I also use STP, which may have something to do with how I got over 200,000 out of a car I bought used.