21st April 2020

Ask An Expert: How To Let A Cold Engine Warm Up

Up next in our 'Ask The Expert' series, we explore the best way to warm up your engine from cold.

Is it better to let a cold engine warm up by letting it idle for five minutes or drive it carefully til it reaches operating temperature ? My Classic is an Alfa Romeo Montreal. - John Gizzi

To answer this, we got in touch with Ged Bermingham from Body & Soul Autoworks based in Cardiff.

“It's previously been thought best to let your oil get to temperature first and get it to circulate, by idling the vehicle for 5-10 minutes before driving. But that no longer holds true as modern oils (and even 'classic' equivalents) have superior blends and technology, such as anti-wear agents and viscosity improvers that:

a) leave a coating - meaning you're not grinding dry metal together prior to the oil pressure building up and

b) aren't as prone to waxing and being unable to circulate properly until warm.

Most conventional wisdom on this was written long before technology moved on.

I believe that it’s better to go with some careful driving rather than sit with it idling, as the richer running also can cause a number of issues including bore-wash, fouled plugs and even bore-score on certain engines. Those suffering the latter tend to be angled engines, i.e. flat 4 or 6 or slant 6 types. This is what I do with my own cars.

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The information contained in this blog post is based on sources that we believe are reliable and should be understood as general information only. It is not intended to be taken as advice with respect to any specific or individual situation and cannot be relied upon as such.

I think I read somewhere that extended, low-rpm idling puts extra strain on the valve train. I always let the oil circulate until pressure shows and then drive gently until the engine is nice and warm.

Dodger, 27/09/2023

driving off straight away gently was the way I was told as a medic ambulance driver in the military 1955-1962, but of course oils have advanced since then and we are being brain washed about leaving vehicles idling because of clean air zones, so I would leave it to the owner.

Dr Baz , 29/04/2020

The handbook for the 1929 Lagonda which I owned from 1959 to 1979 and other handbooks for cars of that era all say it is better to drive away gently until the engine has warmed. I don't know where this idea came from that idling is good for any engine, I've never seen it in contemporary literature.

Bono, 22/04/2020