I'm curious what other people's "engine warm up" routines are. Both my grandfather and dad told me when I was a kid that I should always start a car and let it idle until the water and oil were at 40C or more, something I've always done (with older cars). This reduces wear on the engine, ensures that the carburetor is at it's optimal operating temp to atomize the fuel correctly, etc. I understand that for modern cars (with fuel injection and computer control of fuel delivery, variable cams, etc) it's not necessary or desirable, and the car will warm up as it's driven. But for older mechanical injection motors, and especially carbureted engines, is it better to: 1. let them warm up at an idle (10-20 min) 2. start them, then drive slowly/carefully until they warm up under a (light) load 3. start them and drive, no warmup needed Where I live (cold, wet), it takes about 10 minutes in the 'summer' (i.e. over 15C) to warm up, and 15 or more minutes in the winter (10C down to -10C). I'm not talking about turning on the interior heater or anything, just getting the engine block and fluids warm. I read in a separate thread (Ferrari) that some people recommended (for older classic cars) to start the engine and wait only long enough for the idle to stabilize (i.e. a minute or two at most), then drive gently, staying under 3000 rpms until oil and water are warm. Discussion groups being what they are, there were just as many advocating the opposite, to let it idle until warm. Additionally, is it safe to use an engine warmer on these cars? It's a pretty common sight here on newer cars, it's basically a modified oil plug with a short heating element on it, plugs into the wall, and gently warms up the oil in the sump over the space of a few hours. What do the esteemed and knowledgeable people here recommend? What method do you use with your own car(s)?
All cars need to warm up. I see these guys start a Ferrari, Lamborghini or really any high performance car and then leave their parking spot with a female companion and nail the throttle to impress ... It makes me cringe. The FI just does a much better job of controlling the F/A ratio so that the car drives well even though it's not warmed up. Most people treat their cars like a vacuum cleaner with an on/off switch. An older exotic with a bunch of Webers and a relatively primitive ignition system isn't going to do too well just being left to run at idle. Mine need a little help and I think waiting until the water begins to show on the temp gauge and then driving modestly is a pretty conservative and safe method. The transmissions on some of my cars can take at least half an hour to warm up properly. Your elders taught you well.
I don't think it's best for any car to sit and warm up at idle for a long period of time. Cold idle is usually pretty rich and creates a lot of acid by-product. This can eat at aluminum parts and contaminate the oil, so you should only let it sit at idle until it's warm enough to be driven as it will heat up a lot faster being driven vs. sitting at idle. On new cars, that's right away, on old cars, I'd let them idle until it would come off of high idle (with heat-riser style choke). With electric choke (or no choke), I'd wait until the car could idle smoothly on it's own before driving. Then I'd keep under 2000rpms until the temperature gauge started moving and would not rev over 3500-4000 until fully warm. This worked well for me in upstate NY winters, never had to rebuild an engine. I put 60k miles of daily driving on my trans am over about 3 years (including winters) with that method and the engine had zero issues. It's still going strong with it's new owner. The most dangerous thing for an engine is to be revved when cold, so as long as you don't do that you're probably ok. In a lot of engines, you can shear the oil pump drive shaft doing that due to the thickness of cold oil.
A cold engine has 2 flaws to centend with: Tolerances of the moving parts are not at their intended size, and mixture is far from ideal, condensates on cylinder walls, taking away lubricant and seeping past rings, contaminating the oil. Cold idle is bad for an engine. Best is to wait until the engine takes on the accellerator smoothly, and do the warm-up with the engine under moderate load. This will shorten the warm-up time, cause less contaminants in the oild (pressure on rings/ring-lands) Especially those who have dry-sumped engines need to take extra care, as engine-oil under-performs when cold, and puts huge loads on the oil-pumps when revved too high. Keep your revs down until the oil-temp is well off the peg. With 13 liters of engine oil this takes a while...
My car is a weekend only car and is kept in a garage on tyre pads and covered in a car cover to protect it from dust. I start my car during the week in case my battery conditioner doesn't work properly, and give a blast flatout around my block to get the oil flowing. When I start my car a let the engine idle for 15 seconds and then give some small revs. This also takes 15 seconds. Then I reverse out of my garage slowly and put it back in neutral and rev it bellow 4,000 rpms. Then I let it idle for 2 minutes and then creep out of my driveway and onto the road. When I get onto the main road I give it the beans, unless it isn't coming up to temperature. That's my engine warm up procedure. Then I have a nice crushing drive on my favourite mountain roads and cruise through the city in 1st gear to get some lunch!
Nobody mentioned pre-heating the engine bay - it's a habit that crossed-over from the aviation field. Planning in advance when/what I'm taking out for a drive gives ample time to run an electric heater in the engine bay at least an hour, usually more like 2. No matter the season, but obviously the colder the more difference it makes. The engines fire up far easier, settle down quickly, no nursing needed, oil flows more readily. Less idling for temp to come up. I still wait for full oil and water temp before getting on the throttle hard. The transmissions in the Bora and Plymouths like this too. I pre-heat the Alfa and Aston too, but their rear transaxles take the normal time. Cheers, - Art PS - Besides the temperature, there is also engine lubrication; pre-start-up oiling can be accomplished with a pressure accumulator or electric pump.
