cold oil/ hot engine

[BFG TERRANO]

Took the bread knifes 206 diesel for a run earlier, just to warm it up prior to oil change.
Got back and drained it while still hot. Go in the shed for new oil and re fill. Job done.

Didn't really think about it but- hot engine filled with freezing cold oil. Was this silly? It's been driven since fine but should this be avoided?

[falkster]

Never really thought about it before but why should it be an issue?

[davepoth]

falkster said:

Never really thought about it before but why should it be an issue?

rapid temperature change could conceivably cause a block crack. I severely doubt that it would be enough though - the oil would be a bit above freezing and only goes into the engine relatively slowly.

[BFG TERRANO]

falkster said:

Never really thought about it before but why should it be an issue?

Hot metal, alloy etc being hit with oil barely above freezing. Cracking, damage etc.
Thinking about it I guess no garage has a heated store for oils.

[Robb F]

No, the temperature difference wouldn't be anywhere near enough to causes cracking, especially with oil which quenches a lot slower than water.

[Willy Nilly]

By the time you have pulled into the garage, found all you oil changing gear, removed the plug, dropped it in the bucket, found it again, found the oil filter won't come off, found a bigger set of pliers, swapped the filter and put the plug back in the engine will be cool enough.

[Liquid Tuna]

I'd hope not! If cold oil onto a hot engine, even a steaming hot engine, is enough to cause something to crack, doesn't bode well for the engine under all the other stresses it'll go through in its life surely? Like a bad owner hammering it from cold etc?

[Robb F]

Willy Nilly said:

By the time you have pulled into the garage, found all you oil changing gear, removed the plug, dropped it in the bucket, found it again, found the oil filter won't come off, found a bigger set of pliers, swapped the filter and put the plug back in the engine will be cool enough.

Even at the hottest your engine ever gets it wouldn't crack. The block would have to be glowing bright red before it even got close.

[Willy Nilly]

Robb F said:

Willy Nilly said:

By the time you have pulled into the garage, found all you oil changing gear, removed the plug, dropped it in the bucket, found it again, found the oil filter won't come off, found a bigger set of pliers, swapped the filter and put the plug back in the engine will be cool enough.

Even at the hottest your engine ever gets it wouldn't crack. The block would have to be glowing bright red before it even got close.

Maybe the OP does F1 oil changes in 6 seconds after having the engine at full load

[BFG TERRANO]

Willy Nilly said:

By the time you have pulled into the garage, found all you oil changing gear, removed the plug, dropped it in the bucket, found it again, found the oil filter won't come off, found a bigger set of pliers, swapped the filter and put the plug back in the engine will be cool enough.

I use a suction pump via the dip stick tube so yes, I guess the time taken for the full extraction would drop the temp enough, more so on a frosty morning.

[Robb F]

Do F1 engine block glow under load? I've seen plenty of videos of the exhaust manifolds glowing but never the block. Would be an impressive sight that's for sure!

[BFG TERRANO]

Willy Nilly said:

Maybe the OP does F1 oil changes in 6 seconds after having the engine at full load

Pretty quick but not F1 speed! The extraction pump speeds things up and its saves getting on the floor. It's amazing how quick you can be on a freezing morning!

[falkster]

davepoth said:

rapid temperature change could conceivably cause a block crack. I severely doubt that it would be enough though - the oil would be a bit above freezing and only goes into the engine relatively slowly.

I understand what extremes could do but an engine at operating temp plus very cold oil isn't going to cause an issue.

The only time I've heard or block/head cracking was iced up coolant system due to no anti freeze, engine gets to boiling point due to no fresh water running around then iced water melts then boom.
Quite a lot different.

[Dracoro]

I hope people here do realise that the freezing point of oil is NOT 0!

So, OP, you don't actually mean the oil was freezing cold 0 degrees is the freezing point of WATER.

[falkster]

Dracoro said:

I hope people here do realise that the freezing point of oil is NOT 0!

So, OP, you don't actually mean the oil was freezing cold 0 degrees is the freezing point of WATER.

I don't think it matters what the liquid is, if the engine is at boiling point and a liquid at 0 degrees came into contact something would happen.

I do know you were just being pedantic

[Robb F]

falkster said:

I understand what extremes could do but an engine at operating temp plus very cold oil isn't going to cause an issue.

The only time I've heard or block/head cracking was iced up coolant system due to no anti freeze, engine gets to boiling point due to no fresh water running around then iced water melts then boom.
Quite a lot different.

Frozen coolant cracks the block by thermal expansion. Its what the core plugs are there to avoid.

falkster said:

if the engine is at boiling point and a liquid at 0 degrees came into contact something would happen.

Other than the liquid being warmed up rather quickly, not much would happen.

Edited by Robb F on Sunday 2nd December 17:15

[inman999]

The temperature difference between the oil coming out and new oil going in is at most 80 degrees so no there's nothing to worry about.

[aw51 121565]

Robb F said:

No, the temperature difference wouldn't be anywhere near enough to causes cracking, especially with oil which quenches a lot slower than water.

Oil has a significantly lower 'specific heat capacity' - it will 'take in' much less heat to get up to a certain temperature - compared to water.

Oil's cooling effect is therefore much less than water, and the OP will be fine putting it in a hot engine - it quenches less than water, as you say .