According the my car’s owner’s guide, I should let my car reach ‘normal operating temperature’ before driving hard (above 3500rpm).
As far as I know, the thermostat in most cars measures water temperature (some cars have oil temperature guages - mine doesn’t). Will the water in my car reach operating temperature before the oil does? How much longer should I wait after the temperature gauge is in the ‘normal’ position before driving at high rpm?
On a related note, should I idle my car before switching it off (it has a turbo)? The owners guide doesn’t mention anything about this, and none of the dealers I’ve asked have said it’s necessary. Some people have told me that it’s necessary to prevent turbo failure due to insufficient lubricant flowing through it.
The oil should heat up first as it’s in direct contact with some of the heat producing parts of the engine like the bearings and especially the walls of the cylinders. If the temp gauge for the water shows normal temps then the oil should be warm as well.
But, the reason for waiting for the engine to warm up is based more on the effects of the warm water than the oil. A warmed-up engine allows the fuel injection to operate correctly without the choke circuitry so if you gun the engine with the choke on you’re burning a gas enriched mixture which wastes fuel, fouls plugs and increases emissions.
For the turbo question I’m surprised that the owner’s manual didn’t suggest a little idling time for the turbo unless something has been designed into the engine to make idling no longer necessary (but I doubt it).
The problem with turbos and premature failure is due to the impeller still spinning in the turbo housing even after the engine is shut down and oil is no longer being circulated through the needle bearing. If you shut down the engine and listen for the whine of the turbo it can sometimes be heard to spin for up to 30 seconds and during this time no oil is being circulated. This turns the oil to an abrasive similiar to coke.
I solved this problem on a Dodge Shelby Charger years ago with an electric oil pump that ran for about a minute after the engine was shut down and never had a turbo failure again. This was after replacing the turbo twice in 8 months. New technology could make this unnecessary; new bearing with super heat treated surfaces come to mind or a factory installed pump like the one I added.
But I would still idle for a little if these are not present.
I have driven cars with oil temp gauges and the oil will always reach operating temp after the water reaches temp. It will typically take several minutes after the water comes up to temp before the oil does.
The main reason to avoid high load on a cold engine is that an engine is made out of different materials. Engine blocks out of aluminum or iron, piston rings are steel, pistons aluminum, bearings of multiple metals, etc. All these metals expand at a different rate when heated. The engine is designed to have proper clearances when at operating temp. When cold there is more clearance and bearing play. Some engines even make ticking noises when cold (so called piston slap) as the piston is loose in the cylinder bore until warmed up.
As for idling a turbo before shutting off, this was recommended in the early days but modern turbos have come a long way and don’t require this anymore.
Well, most modern cars will not let you red line the engine when it’s cold. My engine has VVTI-L (a secondary cam system) that does not work when the engine is cold so I can’t use my extra 50 HP until the engine is nice and toasty.
About the turbo, modern turbos like what zwede mentioned do not need to be cooled. The WRX (for instance) does not need a turbo timer as convection will cool the turbo with the car off.
I have never noticed the oil reach operating temp before water temp.
Cold oil does not flow as well as when it is hot and the oil has got to do its job when the thin petal goes to the floor - lots more pressure on the bottom end.
I have always beat the hell out of my Turbo Buick for over 250,000 miles without regard to oil temp or water temp - man it runs good when cold but I would let it idle for a minute if I drive hard before turning it off, or better yet, just drive easy for the last minutes of the trip.
According to the dealer that I bought my Passat wagon from, this is exactly what VW’s 1.8T engine does (in fact, you can hear it happening after you turn off the engine). I specifically asked about it because I was fearing an expensive replacement in my future.
I take it WRX turbos are water cooled. Would the coolent circulating around by its self, as it cools, actually be enough to cool a turbo that has been operating at crazy temps?
I thought it was oil around the bearings that got too hot, causing it to coke…
Do you know of any sites that have this arguement or any proof on it?
I have heard lots of talk, but I do not know anybody that has had the problem themselves.
The turbo timers are considered a waist of time and money among the Turbo Buick people. There is a device that electrically pre and post oils the entire engine. That sounds kinda neat if you must have an extra oiling device.
the engine block is aluminum or iron yes your correct about that but the blocks cylinder is sleeved with steel so friction cant be cause witht the piston and block, or else the block would melt from such high end explosion from the piston.
turbos and regular cars work in a little different ways. first off cars can run cold from the get go and idles and runs better. oil is meant to cool the engine, water is meant to cool the engine too thru means of the water jackets. oil will flow if your in high elevationand it’s snowing out side. ever notice how your car runs better on cooler days than hotter days, thats cause of the cool air, thats how turbos work with forced air injection into your engine.
Canada has already recognized and taken action against auto idling. The city of Toronto, for instance, recently passed a by-law which imposes a fine of up to $5,000 for idling more than three minutes at a time.
idling is just a bad way to warm up your car’s engine because the incomplete combustion creates fuel residue condensation on cylinder walls while also contaminating engine oil and clogging spark plugs, which further increases fuel waste. Moreover, wheel bearings, steering, suspension, transmission, and tires also need to be warmed up, and the only way to do that is to get the vehicle moving.
A turbo timer is unnecesary unless the car is heavily tuned or driven very hard.
Turbo failure happens because there is very little oil at the bearings, so when it is not circulated(ie engine is off) it can burn very fast.
I think the idling time for the turbo to cool down to safe levels can be as much as 10-15 minutes. In heavily tuned cars the exhaust manifold, downpipe and turbo actually get visibly red hot. Thats gonna take some time to cool down
I don’t think the turbo can go on spining for as long as 30seconds after turning the engine off. Since the throttle is closed and the blow-off valve wont open (it needs engine underpressure), the pressure that will build up between the turbo and throttle will make it spin down pretty fast.
a little common sense here. Oil is made to flow through certain areas of an engine as a “lubricant”. What a lubricant does is prevent wear on moving metal parts. Ok? The engine has moving metal parts that fit together with narrow tolerances. If these metal parts rub against each other, they act like sand paper one against the other and cause “wear”. “Wear” is what a car owner seeks to avoid.
Now it is also a proven fact that when oil is thinner it can move into those tiny narrow spaces and lubricate. That is place itself between the moving parts, thus avoiding wear. Oil gets thinner by being heated. (Let’s not get carried away, because too hot also is bad as the oil gets too thin to lubricate)
So a wise owner will let the engine warm up before really giving it the gun, give the oil time to warm and thin down a bit and work its way in to those spaces.
It is said by some mechanics that 90% of all engine wear takes place during the first 10 minutes of warm-up due to the fact that the oil has not been sufficently heated to “operating temps” and thus thin enough to get into all those tiny clearance spaces and do its job of lubricating.
Now having said all this, there are two conflicting theories as to how to reach the optimum temp for the oil. One is to let the motor idle, say for 5 minutes or so before taking off. And the second is to start up and take off right away thus having the oil heat faster.
Ok let’s look at the answers here and talk about them.
The vast majority of the heat in an engine is from the fire burning in the cylinders. The oil is not in contact with this. To heat the oil, the heat has to transfer through the head, into the coolant and then into the oil in the valve train. Below the cylinder the heat has to travel through the pistons, and the cylinder walls in order to heat the oil. The oil reaches operating temp several minutes after the coolant does.
Do not confuse what your car does with what most cars do. My car will red line cold, and the dual VVT system does work cold (to reduce emissions).
A web site? No. Will you settle instead for a guy that teaches this stuff of the factory? In a word yes. Before the introduction of water-cooled turbos on Volvo’s a turbo would last between 50-75,000 miles. Once the water cooled turbo was introduced in 1988 the life expectancy went to the life of the car (assuming proper maintenance of course) To answer you question about coking, what causes the oil to coke is latent heat in the turbo, after shutdown, heating the oil up to the point it is burned into coke. By adding a water jacket around the turbo, the heat is transferred into the coolant instead of the oil, so the oil does not coke. As the heat is transferred into the coolant the warmer coolant rises, and cool(er) coolant flows into the turbo from the bottom. This convection current continues until everything is at the same temp. Simple and bulletproof.
Oh, welcome to the board.
Oil viscosity changes big time with temperature. I have a video at my school of an engine in a lab that has been cooled to -26F After 30 minutes of running the 20W-50 oil had not yet reached the rockers. On another engine in the same test, the 10W-30 oil took 30 seconds to start to flow from the rocker shaft, but when it did it looked like the discharge from a slurppy machine. So I would agree with your statement assuming that the oil is of the correct weight and the oil is warm.
The end of the last article is a good point. Wear on the engine is increased before the engine is warm.
And Rick, VVTI-L “lift” does not work cold but I was wrong to say most cars prevent red lining (my mistake, you can always red line a manual for instance).
About WRX Turbos. They are both water and oil cooled. There’s a lot of talk about turbo timers and WRXs and forums and such.
Abuse your equipment and your equipment will abuse you.
Northen Arkansas, a little heater in the cabin and a magnetic pan heatrer under the oil pan anytime the temps are going to be under 40 F and it will run for a long time. YMMV
How I got a 1/4 million out of my non water cooled turbo I do not know? It still worked as in 20 + PSI with no problem, but I was seeing some oil in the pipes after the compressor.
Yep. I used to run 20W-50 in my 454 cui V8 until one day it took so long for the oil to reach the rocker arm that it galled. The pushrod, rocker arm and ball were all trashed. I replaced the parts, switched to 10W-30 and never had that problem again.
what rick is talking about is what would happen in a non fuel injected car such has older models that doesnt happen now. call up or walk into any manufacture and ask them if you can start you car and drive in any temp. the answer will always be yes.
You can certainly start and drive in cold temperatures. The question the OP posted was if it was recommended to take it easy on the car until it reached full operating temp, and my opinion is still that until the engine has reached operating temp you should not hammer on the car. Keep the revs under control and no more than half throttle. I do not recommend warming the car up by idling before you drive off. It is better to drive off immediately, keeping engine load low to moderate.
A mechanic friend told me years ago that virtually all the wear on an engine occurs when the engine is cold. When you start it and it’s cold (and yes, it’s in fact cold in the middle of a scorching summer, too, which can be hard to remember). He stressed to me the importance of letting the car idle for several minutes…EVERY TIME you start and drive your car.
My habit that I do (unless I’m in a hurry) is let the car idle for a minute or so. Then I put it in gear, but only in first gear, and drive as long as possible until my slow ass is actually blocking traffic on the road…which will happen when travelling at 5 mph. The engine is warming up, I’m moving rather than sitting still, and it’s a LONG route through my quiet neighborhood until I hit a main road.
but I would let it idle for a minute if I drive hard before turning it off, or better yet, just drive easy for the last minutes of the trip.