Did I just hear you say, “I don’t need to wait for the car to warm up, just give it a big rev!?”
Some years ago I used to be awoken early in the mornings by my neighbor revving his car very loudly in his garage. It wasn't pleasant to hear, especially at 5 am! It was a new car that he purchased only a few weeks before. When asking him about it, he said that if he drove off without warming it up it wouldn’t idle well.
His solution was to give it a big rev as soon as it started. That will fix it! Well, yes, and no. It did warm the car up quickly, however, the “start and rev” routine destroyed the engine within months and he was complaining to me what a piece of junk it was and how he had been arguing with the dealer about who was going to pay for the engine repairs.
First a few facts:
- Did you know most of an engine’s wear occurs in the first few seconds of start-up?
- An engine is designed to run for long periods of time within a particular temperature range, usually a couple of degrees above or below 200 degrees F. Tolerances between engine components are optimised for this temperature. This ensures, for example, excellent combustion, good fuel economy, and smooth running. At lower temperatures this is not the case.
- A piston will move and up and down millions of times through a normal engine’s lifetime.
- An engine is designed to use as little oil as possible - if a vehicle used a single drop of oil for each revolution then it would use several gallons of oil per HOUR! Fill up the gas tank please AND the oil tank!
Now, let’s consider what was happening in those first few seconds and minutes during his "big rev"
A cold engine:
The cold engine’s friction surfaces need immediate protection from scraping and grinding against each other. Some protection remains from the previous trip, however, vital oil lines and channels may now have drained into the sump. Once the engine is started it can take a few seconds or more for the oil to circulate and build up pressure which in turn quickly builds up a layer of protection between moving parts. For these precious few seconds vital components lack adequate oil flow to keep the parts from touching. A small protection buffer is available with our modern oils to compensate, nevertheless, this buffer is very small.
The cold and more viscous oil now builds up a lot of pressure. Engineers have considered this and oil bypass valves open to allow colder oil to circulate, usually without flowing through the oil filter. This assists oil circulation and helps to protect the filter and/or oil housing from being damaged. However, we now have a situation where unfiltered oil mixed with microscopic metal particulates and by-products of incomplete combustion, such as sulphur and water, are circulating the engine carried along by the flow of oil. This process abrades and damages the surfaces and the longer and more often than not when this happens more harm is done.
Modern cars have extremely fine tolerances and will not tolerate being subjected to this treatment. In the short term you probably won’t notice too much of a difference in engine performance and wear and tear. But in the medium to long term this will result in significant wear and reduce engine life dramatically.
Moral of the story: Don’t wake your neighbors by revving a cold engine, for their sake or yours.
About The Author: Alan Power
Alan Power, is a father, grandfather, husband, and a DIY enthusiast. He lives down-under in Western Australia and he enjoys spending time with his family and working in his home workshop. Not to mention enjoying maintaining and driving his classic cars.
