Oil change - Hot or Cold?

[Madmal]

Hi all,

 

The 6 has been sat in the garage for a few months so I was pondering the benefits of a cold oil change as, in theory, all the crud would have settled in the sump. If i start the engine for a warm change, the crud would be picked up and re circulated so it may not be the best solution, although the oil would drain quicker. Time, of course, is not so much of a problem as i could leave it overnight to drain.

 

Does anyone have any views either way?

 

Cheers

 

Mal

[BlueTR3A-5EKT]

I have always changed oil after a run when it was hot.

Theory, all the crud will be in suspension or caught by the oil filter, that will be renewed when the oil is replenished.

If you suspect lots of crud then consider removing the sump and cleaning that out - while you are in there, as it is a 6, do the big ends, mains and thrusts, and check the oil pump clearances.....

 

Run engine in the garage after oil and filter change and search for leaks.

 

Peter W

[Fireman049]

+1 for the above advice. You could also consider using a flushing oil?

 

Tom.

[DRD]

Surely cold oil will be very viscous and you'll have trouble draining it all out, especially with any crud in it. Also its preferable to do it when the engine is warm as this ensures all the bearings have a fresh oil film during the change and the new oil can circulate quickly when you restart the engine.

[John Morrison]

Hot, the only way.

 

John.

[Fireman049]

I've always drained my engine oils from a hot engine.

 

Tom.

[Steves_TR6]

Interesting!

 

With a cold engine the oil will come out more slowly but as long as it was hot when stopped surely all the oil and suspeneded nasties will have returned to the sump, so the only downside is time and anything that settled out in the sump?

 

Having said this i do always warm the engine up for an oil change.

 

Steve

[Madmal]

Hot it is then, thanks all

 

Mal

[Motorsport Mickey]

+1 for the above advice. You could also consider using a flushing oil?

 

Tom.

All the guys are on the money here, ESSENTIAL that the oil is hot otherwise the inside of the bottom of the sump is just like treacle. It requires flow to lift and carry out the bits and dead mice that are located in there.

Also as Tom so rightly states a flushing oil (we even added a portion of paraffin back in the day) helps greatly, if the oil is hot and thin it flows, if it flows it carries, ...and out comes the crap.

 

Mick Richards

Edited March 14, 2018 by Motorsport Mickey

[BlueTR3A-5EKT]

What do we think about using oil suitable for diesel engines in the sump of a petrol engine to clear out the crud?

 

Peter W

[Alec Pringle]

Proper flushing oil works a damn sight better, costs a lot less . . . . . but read the instructions and use the quantity required, do not use more than necessary as it won't benefit the engine or your wallet.

 

Cheers

 

Alec

[ShaunC]

HOT! A good run first, drive it like you stole it to get the temperature up!

 

Let it drain whilst you have lunch, a cuppa tea and a slab of cake.

[TR5tar]

I'm doing the service basics at the moment ready for MOT. Oil change next week. I've not used flushing oil before, so what's recommended? I've found Comma XFFO5L X-Flow Flush Out (mineral oil) ... is that a decent one? Also, do I need to do an engine flush first with something like Comma EF400M Engine Flush?

 

Cheers, Darren

 

P.S. I do oil changes hot too, but remember when oil is hot, it's hot and can burn.

[RogerH]

Hi Darren,

I would suggest that your engine does not need flushing. Only after many 10000's of miles will you get a thick sludge on the bottom of the sump.

This is so thick it will sit there and not go anywhere. You will not have any of this.

 

 

Simply get engine hot

Drain oil

Replace filter

Refill with oil of your choice.

 

 

Sometimes the flushing process can remove muck that is serving as an addition seal. Remove this and you have leaks.

 

Roger

Edited March 16, 2018 by RogerH

[Mike C]

I agree with Roger , flushing may have been necessary 50 years ago before oils with good detergent properties were available.

 

I tried some very high detergent diesel engine oil once a long time ago and it opened up leaks in all kinds of unexpected places.

[TR5tar]

Thanks Roger / Mike. Advice taken!

[Waldi]

When I removed my sump, there was a 3-5 mm thick layer of deposits.

I would not want this to be dissolved.

It probably also contained wear particles, that would gave past the oil pump.

Also, if deposits get suspended from for example the oil galery, damage to the bearing shells may occur.

Each to his own I guess on topics like this one.

Regards

Waldi

[Motorsport Mickey]

When I removed my sump, there was a 3-5 mm thick layer of deposits.

I would not want this to be dissolved.

It probably also contained wear particles, that would gave past the oil pump.

Also, if deposits get suspended from for example the oil galery, damage to the bearing shells may occur.

Each to his own I guess on topics like this one.

Regards

Waldi

Solution...drop the oil cold.

Remove the sump and scrape out the layer of crap stuck on the bottom and wash out by hand with paraffin or diesel, replace sump and add any old oil AND flushing oil. Run engine, go out for a short drive with restricted revs (no more than 3000 revs) even, then drop the oil again which hopefully scours out the oilways as well.

 

Me...I just stick flushing oil in and drop the lot in one when it's hot...it's not a watch.

 

Mick Richards

[Mike C]

Change the oil and check the dipstick after the first long hot run. If its discoloured you still have crud in the sump.

 

Personally I have not seen solids build up in the sumps or rocker covers of vehicles with even any slight degree of maintenance for years-which is a tribute to modern oils.

[Alec Pringle]

Leaks after flushing ? That's why flushing oil should be used, the tool for the job, NOT NOT high detergent diesel oil . . . . . . and the proprietary additives won't (at least in my experience) do more than half a job - although Forte is better than most, as with most of their additive range. Pro product that costs proper money, you get what you pay for.

 

In the UK, many TRs are laid up through cold winters after a summer's use of relatively short journeys, and the deposition rate is significant - very different from the real TR man like Roger who regularly takes his car on runs for hundreds of miles, and suffers minimal deposition as a result. I've seen enough removed sumps to know the difference, the internal coating tells you how the car has been driven.

 

Comma flushing oil is good stuff, I've used Comma for flushing for decades - over the years the volume required has changed, as in long ago it was only 50% of the normal oil capacity, but nowadays it tends to be 75% or more - read the instructions on the can !!

 

In an ideal world I'd drop the sump cold as per Mick's suggestion, and clean it out first - that isn't always an available option.

 

The sump will always refit perfectly if you make the effort to clean both mating surfaces rigorously and correct any minor deformation of the tin sump, use a minimum of sealant, and refit by torqueing up the bolts progressively and o'clock, as per refitting wheels or whatever.

 

My technique then has always been to replace sump, get the engine HOT, drain, replace filter, and run as described by the flushing oil instructions (repeat, different brands do vary in their recommendations, the manufacturers probably know their own product better than you or I).

 

Then drain and replace filter, again.

 

Fill the engine with whatever cheap 'high mileage fleet oil' 20W/50 is on offer at the local factor and take the car for a decent fast run, like 50 miles.

 

Once more drain and replace filter.

 

Refill with normal oil and you're good to go . . . . .

 

Yes I'm sure it is all a bit too much like hard work for many owners. You get out what you put in. I expect engines and transmissions to run 6-figure mileages when properly maintained - they do for me, and have been doing since the 1960s. In the days when I managed race teams, we were there to win, which meant proper maintenance and no corners cut. I never ever suffered a lubrication failure in engines or transmission, which I attribute simply to following the 'belt'n'braces' approach as above.

 

Of course the lazy know-all in your local pub might know different, especially if he's spent too long on the internet becoming an eggspert rather than in the pit or under the ramp getting his paws grubby..

 

Cheers

 

Alec

[TR Paul]

Hi, I'm thinking of following Alecs' flushing scheme (I've owned my '6 for over 10 years, and I've never dropped the sump). I've got some 'antique', possibly 15-20 years old. B&Q 20/50 oil (to use after the flushing oil).Would this oil be safe to use, or can it go off? Also, will this process be safe to carry out with the oil cooler?

Cheers,

Paul.

[Cew]

Mad mal,the OP of this thread, only says the car has sat for a few months in a garage, but when was the oil last changed and what mileage has it done since? it may not need an oil change at all.

Edited March 23, 2018 by Cew

[Motorsport Mickey]

Mad mal,the OP of this thread, only says the car has sat for a few months in a garage, but when was the oil last changed and what mileage has it done since? it may not need an oil change at all.

Even if it's only done a couple of hundred miles it's possible it's got acidic content in the oil from when it last started (?) and run, I'd carry out the processes that's been discussed and get rid of it, why mess about with a simple process that costs bugger all ?

+1 with the flushing and use flushing oil in with the B&Q oil, best possible outcome on all fronts, let B&Q at last be of use for something !

 

Mick Richards

Edited March 23, 2018 by Motorsport Mickey

[Cew]

Probably best but my car stands for a few months sometimes and in the 10 years I have owned it has only had scheduled oil changes, only does about 2000 miles a year and only uses Comma 20/50.. I think modern fuels and oils are a lot less "dirty" then when these cars were new, when was the last time anyone decoked an engine simply because it needed it? and not as part of a rebuild.

Edited March 23, 2018 by Cew

[Alec Pringle]

Hi Paul,

 

engine oil does indeed 'go off' with time, and personally I wouldn't let 15-20 year old oil anywhere near the inside of engine box or diff . . . . . . the saving of the cost of a can of oil isn't worth the risk. No way !

 

You'll need to get everything good and hot for the oil cooler to open up and start flowing through, and I'd be looking to flush the system right through including the cooler . . . . . occasionally a cooler is mounted a sump level, in which case it's worth dropping and cleaning separately to shift what will be glued-on internal sludge just as in the sump.

 

Cheers

 

Alec