Cold Oil, Oil Change

[Kidbeen]

Is it always necessary to change oil that is hot? If I change the oil in my 300tdi gearbox why can't I change it when it is cold? Afterall, it is a thin ATF oil and you would think that most of it would drain out.

[PhilipA]

I think the main idea is that any debris in the oil will be mixed in again by the churning about of the engine, gears or whatever and not maybe rest in the bottom of the sump/gearbox.

I usually drive my car around the block so the oil is warm not hot , which I think is enough to suspend the debris.
Regards Philip A

[loanrangie]

No, it just flows better when its warm (not hot) so it comes out quicker. I usually do it after cooling down for a few hours after a run so as not to remove any skin from my body.

[harro]

I don't think there is much advantage, when it's cold most of the oil has all drained to the sump anyway.
What I do do is open the filler cap before I drain the sump, this increases the flow out and introduces a flushing type effect.

I guess the ambient temp might come into play if it was really cold.

Paul.

[rick130]

I think the main idea is that any debris in the oil will be mixed in again by the churning about of the engine, gears or whatever and not maybe rest in the bottom of the sump/gearbox.

I usually drive my car around the block so the oil is warm not hot , which I think is enough to suspend the debris.
Regards Philip AThis is my theory too.

[Rick1970]

This is my theory too.

And mine...only drain cold if unavoidable.

[llandro]

Regarding gearboxes/transfer cases, a wise person once told me to remove the filler plug before you drain the oil.
When things don't work out as they should, its not easy to refill back through the drain hole. [bighmmm]
mike

[Kidbeen]

Regarding gearboxes/transfer cases, a wise person once told me to remove the filler plug before you drain the oil.
When things don't work out as they should, its not easy to refill back through the drain hole. [bighmmm]
mike

What a good idea!

[scarry]

Regarding gearboxes/transfer cases, a wise person once told me to remove the filler plug before you drain the oil.
When things don't work out as they should, its not easy to refill back through the drain hole. [bighmmm]
mike

I was told that as well,

And the wise guy also added,always check the level at the same time,before draining any oil,it will give you an idea if anything is going on.

[PhilipA]

And the wise guy also added,always check the level at the same time,before draining any oil,it will give you an idea if anything is going on.

An alternative to that would maybe just look under where you park your car every few days. LOL

Although a level check will tell whether a leak is from gearbox or rear main seal.
Regards Philip A

[rick130]

And it freaks you out when you undo the filler plug and over half a litre of oil drains out and it's a grey sort of colour!

Happened the first time I serviced the front diff on a Defender a very long time ago.
The swivels had been overfilled with One Shot (really clever deleting the level plug Land Rover!) And so had blown through to the diff compartment.

[trout1105]

Regarding gearboxes/transfer cases, a wise person once told me to remove the filler plug before you drain the oil.
When things don't work out as they should, its not easy to refill back through the drain hole. [bighmmm]
mike

I find it better to just loosen the filler plug and leave it in place so that you don't get a big "Gush" of oil all over your hand when you take the drain plug out [thumbsupbig]

[simmo]

This is my theory too.

x2


yep if there's particles there and you stir up the oil and drain it you can pull them a lot of them out with the oil.
if you leave the oil to sit the particles will settle to the bottom. the thinner the oil the faster they'll settle.

When we take oil samples from transmissions they are always running when we do it so we see the oil that's in circulation.

cheers simmo