When does the most engine wear occur?

[TooManyWheels]

Let me throw another element into the cold start debate.

If engine wear is greatest at start up, then why are vehicles, even electronically controlled ones, programmed with such an unusually high idle speed at this critical time?

 

[JonS]

i was thinking the same thing when it was -20f here, my cars when first started idle at 2000-3000 rpm's - ouch!

 

[Patman]

quote:

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Originally posted by TooManyWheels:
Let me throw another element into the cold start debate.

If engine wear is greatest at start up, then why are vehicles, even electronically controlled ones, programmed with such an unusually high idle speed at this critical time?

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It's an emissions related thing. Apparently it helps the catalytic convertors warm up faster, therefore reducing emissions.

I agree that most of the engine wear occurs within the first few minutes of operation, which is why it's important to choose the right viscosity oil (not using 15w50 in winter for instance) and it's also important to drive very gently during the first few minutes.

You'll also get a lot of engine wear all the time if you choose the wrong viscosity and type of oil too. If the oil is too thick or too thin for your application, then every time you drive the car hard your engine is getting more wear. If you choose the right viscosity and the right brand of oil, you'll see very little engine wear once the oil is fully warmed up.

[ March 18, 2003, 08:49 AM: Message edited by: Patman ]

 

[Ron-Indy]

Thanks for the replys.

Has anyone done an oil analysis pre & post pre-oiler installation to document benefit?

 

[Shannow]

I attended a dinner a while back with an ex Castrol (Oz) chemist, who was part of the team doing the work on "Magnatec".

His explaination was that at start, things are dryish, but quickly establish very strong films of very thick oil. When they're hot, the friction modifiers are at their best, and that the wear takes place in the period between not too thick, and poor action of friction modifiers.

As to the smaller filters, Gneral Motors Holden did install smaller filters on their 6s after customer complaints on tappet rattle in a 1980s car that was competing against imports. The smaller filter reduced tappet rattle to a large degree.

Tooslick, been thinking the same thing on the bypass issue with cold oils recently. If the bypass is open at high revs, then it must certainly be open at low revs with cold thick oil.

 

[Jim]

I have driven a lot of miles in my 40 years of driving and I have only worn out one engine. The other cars went to the junkyard with perfectly good engines.
The engine that I did manage to wear out was a V6 in a Cougar. It had a constant problem with the sensors and the engine ran too rich quite often. A little gas getting into the oil especially on the cylinder walls is very bad thing.

Keep the dirt out, the TBN up, and the other contaminates out and the engine will go almost forever. Cold starts are only really a problem if you don’t let the car warm up. A longer trip will warm up the engine and drive out the moisture. The moisture that forms in the first part of the trip will not have time to do any damage. If you make a short trip and never get the engine warmed, the moisture will stay in the oil for a long time after you shut it down.

Think about how long oil stays in a transmission. My Mercedes manual says that the oil in the transmission never needs to be changed. It has 15W40 engine oil in it. The reason the oil can go almost forever is that the transmission doesn’t produce or inhale water or dirt and is not exposed to temperatures that make it evaporate. The transmission sees just as many cold start ups.

 

[S2000driver]

quote:

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Originally posted by Jim:
The moisture that forms in the first part of the trip will not have time to do any damage. If you make a short trip and never get the engine warmed, the moisture will stay in the oil for a long time after you shut it down.

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So true. Think about what forms when moisture and blow-by contaminants are combined... ACID! When you don't get your oil up to temperature on short trips, your engine actually corrodes faster than it wears!

 

[Ron-Indy]

The comments on an engine "lasting longer than the car will anyway" make sense from a typical use standpoint. I had a 1994 Chrysler minivan that I ran Mobil 1 in since I picked it up from the dealer. 100,000 miles later when I sold it (only changed sparkplugs once and one spark plug wire) I couldn't wait to take off the oil fill cap to show the prospective buyer how new looking the rocker arms were. He wouldn't even stick his head under the hood to look. Really aggravated me.

Anyway, I ask these longevity / pre-oiler / wear questions because I plan on keeping my current "toy" vehicle forever. The engine costs upwards of $17,000 to replace (no idea on rebuild cost), so any tips I can learn on minimizing engine wear will payoff for me years down the road.

Again, thanks for the comments.

[ March 18, 2003, 08:15 PM: Message edited by: Ron-Indy ]

 

[Dr. T]

This is something else I've been saying for a long time...engine wear doesn't really take place all that much at start up. Unless you start your car once a year, there will always be a layer of oil on every component. How much oil do you guys think you need? 2-3k rpm on an engine w/o a load isn't a big deal. Remember, the Aunt Millie test...

I agree, it's most from poor maintenance. Please don't add misinformation here like saying that 15-50 is too thick, etc. We have not seen this at all. We have only seen thinner oils breaking down and causing engine disasters such as the Toyota issue.

Otherwise, it's correct, the filter size is not an issue because all filters should be full when starting the engine ensuring immediate oil pressure. In fact, a larger oil filter should provide additional filtration, a good true.

I will say though, that the number of cold starts has an effect on the life of an oil and may increase it's contamination relative to a car that does a lot of highway travel. Again, a maintenance issue.