Piston Slap: Improper Engine Warm Up Procedure?

TTAC Commentator Arthur Dailey writes:

Sajeev,

Thanks very much for posting my question. Your answer and the comments from others were most informative. How about another?

We now have only 2 licensed drivers in our home. We do however have 3 licensed cars in the driveway. Please do not ask about the project car in the garage. 2 of the cars are our ‘daily’ drives, the 3rd is used primarily on weekends. We live less than 3 minutes from a 400 series highway in Ontario. That means that the cars can be required to reach highway speed before they are ‘warmed up’.

My normal practice last winter was to get up, start all the cars, turn off all possible drains on the batteries. Then take the dog to the park across the street, stretch our legs and let him do his business. After about 10 minutes we return. I then turn on the heater/defrost on the 2 cars that we will be driving and scrape/brush them. When this is completed, I turn all 3 cars off and go back into the house to get myself ready for work. You may all remember what last winter was like and the upcoming winter is supposed to be similar.

Now I understand that idling is environmentally irresponsible. And possibly against by-laws in some areas. That however is a discussion for another forum.

My questions are:

1. Is this OK for the cars?
2. Am I better off warming up/idling our weekend car like this or leaving it all week and hoping that it is OK to start on the weekend.

Please do not suggest:

1. A trickle charger
2. Engine block heaters

I would love to have those as options, however none of the cars have block heaters installed and there are no electrical outlets available for either of the above suggestions (thanks to the project car).

Thanks,

Sajeev answers:

Okay! I will not mention your Project Car, nor your need for conventional starting aids in cold conditions. Even if your engine warm up procedure absolutely demands otherwise!

In general, start-up a cold motor and drive it ASAP in a modest, moderate manner. What does that mean?

Perhaps that means not accelerating past the motor’s torque peak, unless necessary for merging onto a freeway. If you own a torque-less, rev-intensive motor à la Scion FR-S, the torque peak notion is invalid. No matter, avoid heavy throttle application until oil temperature is up to normal: think about your unique engine type/driving condition and apply common sense.

Thanks to advancements in fluid technology and the widespread use of synthetic-blended oil, it’s gotta be disturbingly cold ( handy chart here) to do otherwise. On to your questions:

1. Why are you turning off the cars after warming them up? No! Do your stuff while they idle/thaw (when needed) and then drive! You are only hurting them more by letting the fluids cool down again. Change your morning routine ASAP.

2. There is no reason to start-up your weekend car just to charge the battery. If the weekend car is impossible to start after 5 days, get a battery blanket (Oops! No power right?) and disconnect the negative cable to minimize drain. Or just give up and yank the battery, leaving it somewhere isolated from the ground, like a wood table. More work, but if you can physically handle that heavy of a load, the exercise won’t kill ya.

No matter what, you gotta change your warm up procedure.

Bonus! A Piston Slap Nugget of Wisdom:

Remember that oil temp isn’t measured on the (coolant) temperature needle on your dashboard. Oil takes longer to warm up, so if you aren’t fortunate enough to have a sub-menu showing oil temp, or you don’t have an app for that, wait a little while after the temp needle is happy. That makes the oil happy too.

[Image: Shutterstock user Pixelcruiser]

Send your queries to sajeev@thetruthaboutcars.com. Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.