Absolutely DO NOT USE that product.
Who told you the oil was badly sludged? If the oil was sludged, that really isn’t a problem, its when the engine gets sludged that its a problem. It is possible to go 20,000 miles on an oil change without any serious damage, especially in a fairly new vehicle.
There are a couple of factors here, first is the breakdown temperature of the oil. If you never exceed this temperature, the oil never breaks down. Back in the mid to late 70’s, engine oil temperature ran about 305? but the typical 10w40 oil popular at the time broke down at 295?. Add to that, a major manufacturer was recommending oil changes every 7500 miles and many engines sludged up by 40-50k miles.
Most oils today are good up to about 350?, synthetics go up to about 450?. Even synthetics will break down when exposed to temperatures higher than they are rated for. While the average oil temperature is usually lower than the oils normal breakdown temperature, there are hot spots in the engine. While passing over these hot spots, the oil may momentarily exceed its breakdown temperature.
Breakdown is a combination of time and temperature. The higher the temperature over its breakdown point, the faster it is damaged. Momentarily exceeding the breakdown point by a small margin won’t destroy the oil, but it does a little damage and the damage is cumulative. Thats why the oil needs to be changed periodically.
Most of the damage to the oil occurs at shutdown, particularly a hot shutdown. A small amount of oil gets trapped in these hot spots and doesn’t get flushed away until the engine is started again. This small amount of oil takes a big hit, but on the next start up, it gets mixed in with the good oil, contaminating it. Contrary to popular belief, city driving is no harder on oil than highway driving. Its just that city driving usually has far more shutdowns per 100 miles than highway driving.
The biggest problem with sludge build up in engines is at the top of the cylinder head, just under the valve cover. Its a really big problem when it plugs the oil return holes, that traps oil and prevents it from getting back to the oil pan. In some cases, the oil level in the valve train area rises above the valve stem seals and oil gets sucked into the combustion chamber.
My recommendations for you is to use an approved oil, change it as often as you feel comfortable, do not use any flushing chemicals or any additives.
The reason I do not like auto-rx is one of their testimonials was someone claiming that it worked so good that it turned the oil in a brand new engine black in 500 miles. This person attributed it to cleaning out the junk left in there by the factory. Having worked in a factory that made cylinder heads, I can tell you that modern engines do not have any junk left in them, they are absolutely clean when they leave the factory. If the oil turned black after 500 miles, it was the auto-rx itself that caused it.
BTW, the engine does not need a complete disassembly to get the sludge out, but it does require enough disassembly that it is not economically viable. The cost/benefit ratio does not justify the expense.
I’m in agreement with the same mountainbike and think your engine is damaged goods.
If the vehicle were mine I’d drop the oil pan and remove a few rod and main bearing caps (preferably caps located furtherest from the oil pump), and see if the overlay is wiped out. Odds are it is.
This is not a difficult job to do at all and if the bad news is present as I suspect, it’s time for an engine or keep it close to the house until it dies an early death.
No amount of flushing, cleaning, or additives will cure anything once mechanical damage occurs. Increase oil flow to what? Damaged parts?
keith; you are right about the temperature part. However, the additives in oil get used up and can no longer keep the contaminants in suspension. The oil will sludge up even without thermal breakdown. However, if the oil circulates poorly, it will defintely overheat (hot spots)and break down; how much we don’t know. The purpose of an oil is to lubricate, clean and COOOL!
Some engines can run longer before “sludging up” than others. The advice given here is to apply a number of short spaced oil changes, and let the detergent in the oil gradually free up ths solids and then drain them.
So, the best OP can do is to get as much of the crud out as possible without disassembly and hope for the best.
Your proposal is OK for you as you do your own work, the OP has to pay someone. In his case, the cost/benefit ratio does not justify this. Frequent oil changes without using additives is his most cost effective option. The engine might run just as good as it is today when he gets the “new car bug” again.
My point is that it might be worth the expense of knowing for sure. It would seem to me that a couple or three hours of flat rate time (several hundred dollars and maybe done at the next oil change when the oil is drained anyway?) should cover a simple pan drop and the removal and installation of a couple of bearing caps. Preferably several caps at the far end of the crankshaft in which the bearings will be on the tail end of the oil pressure supply.
If the OP pretty much sticks around town I suppose he could let it slide, but if the car passes the city limits signs on occasion it would make me a bit nervous due to the possibility of a death rattle developing or a catastrophic and sudden failure.
It would also be a good idea to keep tabs on the oil level to make sure an oil useage problem has not become a severe one.
Thanks for these suggestions. I’d be willing to have this done to find out what is damaged. If the bearings are damaged can they be replaced, or is it likely thats just an indicator that the rods are next?
I’d say do that AND take off the valve cover, because then you have access to a significant portion of the places where sludge would be a problem, so you could mechanically remove a lot of the sludge. Not sure how hard this is to do on that car, though.
Toyotas are renowned for their ability to survive sludging.
edit: And some are also reknowned for their ability to simultaneously PROMOTE sludging.
The two things you have to worry about when trying to remove sludged oil from an engine with frequent oil changes are, the sludge in the heads doesn’t break off in chunks and plugs the oil drainback holes, and that the oil pump pickup screen doesn’t get plugged up with the sludge. If either of these happens, it’s instant death to the engine. That’s why it’s better to take the engine apart and clean it to prevent that from happening.
Tester
The turbo on the CX-7 is fairly small compared to some others(full boost at 2500 rpms), so sludge in the turbo is also another major concern. Even if the engine is ok, if the turbo is cooked, then you’ll have a ticking time bomb on your hands