5th Apr 2011, 19:45

"The heat gauge indicated a drop of 5-10 degrees in coolant temperature. Since running slightly cooler is actually BETTER for an engine"

Running an engine at a temperature that is lower than the normal operating temperature can cause the engine oil to sludge. And you say you're a mechanic? How long have you been retired? Because every up-to-date technician knows that CHECK ENGINE lights are not preset to come on at certain mileage intervals. A CHECK ENGINE light will only illuminate when a specific problem with the vehicle has been detected by the computer. No Auto company makes the lights come on just to try to get money out of you. Sorry to burst your bubble.

6th Apr 2011, 13:22

Not true. Many cars "check engine" lights are pre-programmed to come on at programmed intervals to get the owner to bring them in for service. Chrysler did this beginning in the late 80's.

As for a 10-degree drop in temperature causing oil sludging... hardly. Modern synthetic oils do not sludge under any conditions other than possibly coolant contamination. Running cooler does not cause coolant to leak into the engine oil. I put a piece of tape over the annoying illuminated light in my Chrysler and drove it another 135,000 miles with it illuminated. If it had a "problem", it sure took a long time to cause any trouble. I sold the car running perfectly at 180,000 miles with never a repair.

And incidentally, who do you think teaches "up to date" technicians that you need to bring your cars in every time the "check engine" light comes on? You guessed it... The SAME manufacturers who make billions off the whole scam. Gee, I wonder if there just MIGHT be some vested interest in that??

26th Sep 2011, 21:30

LOL too funny! Any car that runs at 160 to 180 degrees is perfectly normal. Oil sludging, haha, you're kidding right? You have been watching those commercials eh! Only after it's been in the engine for 2 or 3 years will it do the sludge thing :) It is true.. check engine lights make manufacturers millions!..

13th Nov 2011, 22:22

Just bought 2004 Ford Ranger Edge with 89K. The truck was almost empty, and the dealer put gas in it before I drove off lot. About 20 minutes later, check engine light came on. Dealer has checked and cyl. 4 and 6 are dropping too much gas. They added Seafoam injection cleaner, but the light still comes on, but goes off and on, and sometimes blinks. Any ideas?

24th Nov 2011, 23:00

You seem to be confusing the "check engine" light with the "maintenance required" light; the latter is programmed to come on at certain mileage intervals to remind you to change your oil/filter and perform any other required maintenance. Rather than putting a piece of tape over it, it could have been reset and turned out very easily.

26th Nov 2011, 13:26

To comment 23:00: Nope, no confusion at all. It IS the "check engine" light. I'm a mechanic. I know which is which. If the car continues to run smoothly, loses no power and doesn't suffer a drop in fuel economy, the light can be ignored...PERIOD. These lights are not only overly sensitive, but are pre-programmed by manufacturers to get you to bring the car in and spend money at the dealership.

Two of my three cars has had the "check engine" (NOT the maintenance) light on for 5 years in one case, and 2 in the other. One codes as "running too cool". That car actually runs BETTER and gets better fuel mileage now than it did 2 years ago before the light came on. It has a heat gauge that indicates a 5-10 degree drop from the normal range. This actually causes less stress on the engine. The heater still warms the car up in the same length of time, and my oil will break down more slowly at the lower temperature.

The older car has had the "check engine" (NOT maintenance) light on for 5 years and it codes as "EVAP system" This is a catch-all category that can mean anything from a loose gas cap to a leaking hose in the pollution control system. In my case, it has not effected mileage, power or smoothness of the engine. Those are the parameters that I base my assessment of any need to make repairs on.

If there is a real cause for concern when a "check engine" light comes on, you'll notice definite symptoms within roughly two weeks of driving. Clogged converters (very rare) or dirty oxygen sensors will cause noticeable effects, such as power loss, rough engine, or overheating. anything else can be ignored. A poorly fitting gas cap will cause nothing except the light coming on.

My experience has shown that both Ford and Chrysler products tend to be programmed to light up the "check engine" light at regular intervals. In the case of my Dodge, I could simply reset the light and it would remain off for exactly 40,000 miles, then pop on again. It was so regular I never even bothered to run the codes on it. There was never a problem.

I have reset the light on several of my Fords by simply running a tank of premium gas through it (premium is much better for the car, and serves to not only give it a mileage and power boost, but also helps clean the engine due to the higher combustibility).

27th Nov 2011, 13:34

If the CEL is programmed to come on at regular intervals, then what is that interval?

If the CEL comes on as a result of the interval, how can it go off after using a tank of better quality gas?

I don't doubt what you are experienced, but your conclusions are not making 100% sense. But 90% is pretty darn good!

28th Nov 2011, 19:41

Chrysler used a 40,000 mile interval for their CEL's to come on. A Chrysler service tech told me that, and showed me the way to turn the light off using an off-on code with the ignition key. This was on a 1990 Dodge. The light came on like clockwork at 40,000, 80,000, 120,000, 160,000, 200,000 and 240,000 miles. We sold the car at just over 240,000 miles, and I warned the buyer that the CEL would come on at 280,000 miles. It did, and again at 320,000 miles.

Most CEL's are set to come on at around 40,000 miles, because that is when the bumper-to-bumper warranty is out on most cars, and then the dealer can charge you for it. And no, running a tank of premium WON'T reset the light if it comes on because of a pre-programmed command. You'll have to rest it manually. In order to make more money, Ford uses EXTREMELY sensitive CEL's that will come on at random for almost nothing at all. I have had a number of friends who had the light come on on their Fords, and it went off after a tank of Premium fuel or a can of injector cleaner.

It's a very simple matter to go by Auto Zone and get the code run when a CEL comes on. In most cases it is nothing. The last code I had run on mine, I was told "I wouldn't bother with it, it won't hurt anything." That was 40,000 miles ago, and the car still runs flawlessly.

I'm ordering a device to use to blank out the "nuisance" coding on my CEL's so they won't light for pre-programmed intervals or "nonsense" trouble codes (codes that don't indicate anything that will harm the car). Ideally, I'd like to just unhook the CEL entirely, as anyone who knows cars doesn't need one.