Think of the oil like the wash water you use to clean your kitchen floor and the inside of your engine like the floor itself. The engine has continually cleaned the inside of your engine and now carrys the dirt out with it, just like your wash water does for your floor. That’s a good thing. The oil is dirty, so the inside of the engine must be clean.
One of the functions of the oil is to carry away contaminants and microscopic particulates. It washes down the insides of the engine, particularly the cylinders, as it works. My analogy is not as far fetched as you may think.
I’ve got some altered views here on some things mentioned.
First the $150 engine flush is probably the guy wanting to sell a chemical or pay for a machine. One machine is quite expensive …and thorough, but unless you had some sludge prone engine that was sludge laden, I can’t see it having a purpose.
The trans fluid exchange is great and should be done in a timely manner. It’s easy enough for a DIY’r …but expensive to have a provider do it. You’ll pay mark up on the fluid plus the labor. Much more economical to do yourself.
The brake fluid thing never worked with me. No mechanic I know does it for anyone. There’s no OEM recommendation for it on a domestic, at least up 2002-5’ish to my knowledge. Some of the Euro’s do recommend it.
The reason is simple for most consumers. They’re getting the brakes bled every 2 years for the brake job that they waited too long for. That exchanges enough fluid to keep most systems intact for 20+ years. The problem would arise with a DYI’r who may preemptively do a pad slap before the rotor need cutting and never disturb the hydraulic side of the system for 8 years.
If you want to decoke your rings, and clean up your trans before a fluid exchange, Auto-Rx would be a product to look into. You merely add it at the beginning of the oil change and go about your business. It’s got ester components that are highly polar and want to bond to metal. Redline oil uses one of the components as its base stock. In a trans you just add 6oz about a 1000 miles before your fluid exchange. Transmissions are easier/faster since they aren’t subjected to combustion temps/processes.
That’s a great analogy! I never knew oil had a cleaning role. I thought it was just to lubricate the surfaces.
And I always got it changed at 3,000 miles! If I was late, I’d see how dark the oil was on the dipstick and be very worried about it until I could get it changed. Thank you all for the tremendous peace of mind!