Flushing oil - Richard Shutt

Is the use of flushing oil recommended. I know this has been discussed before but I don't recall a consensus being reached except that it was probably not a good idea with a high mileage car as it could unblock something that was better left blocked!

But what about low mileage cars? If you stick to HJ's recommended oil change intervals is there any point?

Also it is safe to use Flushing oil in an engine with hydraulic tappets? In the past I've read that it is good to use it with such engines as it can remove particles that are blocking the free flow of oil into them, I've also read that it shouldn't be used as it is incompatible with their mechanism!

And while I'm here what about those "add to oil before changing" flushing additives? If your car doesn't use any oil then that means you're overfilling it but does that matter for 15 mins on a fast idle?

TIA

Richard Shutt
Re: Flushing oil - honest john
The term 'flushing oil' usually refers to the additive rather than to a special fill of thin oil. The best flushing oil of the lot is a 'fully synthetic' such as Mobil 1 which will find and flush out all sorts of old crud. The trouble is, if it dislodges a big lump, this could clock an oilway somewhere between its departure point and the filter. That's why if you switch to fully synth after 70,000 miles or so you will haver to change it several times before the oil stays clean. But if you stick to 5,000 mile oil change intervals, unless then engine is turbocharged, you will usually be getting rid of the old oil before any of it carbonises and turns to lumps of crud. If it is turbocharged and you don't simmer before switch off, there is always the possibilty of coking you oil in the red hot turbo bearings.

HJ
Re: Simmering turbos - Stuart Bruce
honest john wrote:
>
> If it is turbocharged and you don't simmer before
> switch off, there is always the possibilty of coking you oil
> in the red hot turbo bearings.
>

I have always simmered the turbo before switching off unless the couple of miles before stopping have been particularly steady. But a self professed expert told me as it was a diesel it was a waste of time as diesel turbos run cooler. I know the last bit is true that they do run cooler, but surely there is still the possibility to coke up the bearings?
Re: Simmering turbos - David Lacey
I always let the engine idle for a minute or so in my diesel cars to allow the turbo to loose speed before shutdown, less so if the last mile or so was at low speed as Stuart rightly states.
Re: Simmering turbos - David Lacey
'Simmering' a turbo-charged car is allowing the engine to idle for a minute or so, especially after a fast run to allow the temperatures to stabilise within the turbo - if the engine were shut down without simmering, then the oil contained within the turbo would cook and form a black sludge, which is not good news.

The second reason to simmer a turbo engine is to allow the turbine/compressor shaft to slow up a little. Again, if the engine were shut down to quickly, the shaft would still be spinning at 100 000rpm plus, without any oil pressure for lubrication. These shafts literally 'float' in oil when running.
Again, if this happens, seriously bad news for the wallet.
Re: Simmering turbos - Dave
David Lacey wrote:
>
> 'Simmering' a turbo-charged car is allowing the engine to
> idle for a minute or so, especially after a fast run to allow
> the temperatures to stabilise within the turbo - if the
> engine were shut down without simmering, then the oil
> contained within the turbo would cook and form a black
> sludge, which is not good news.
>
> The second reason to simmer a turbo engine is to allow the
> turbine/compressor shaft to slow up a little. Again, if the
> engine were shut down to quickly, the shaft would still be
> spinning at 100 000rpm plus, without any oil pressure for
> lubrication. These shafts literally 'float' in oil when
> running.
> Again, if this happens, seriously bad news for the wallet.

It should be noted that these techniques are *not* required for company cars or hire cars.

Unless you intend to buy it at some point in the future...

;-) ;-) ;-) ;-) ;-)
Re: Simmering turbos - Stuart Bruce
Dave wrote:
>
> It should be noted that these techniques are *not* required
> for company cars or hire cars.
>
> Unless you intend to buy it at some point in the future...
>
> ;-) ;-) ;-) ;-) ;-)

but seriously, just to be a boring old f*rt, ( when *is* somebody going to start an old f*rt's thread? oh all right I will start it later tonight) even if its a company car you can be seriously in the brown and murky if you pull into the m'way services just once after a hot and sweaty thrash and switch off immediately. Come out after your burger & fries its possible that that the turbo is knacked. So its not just a long term issue. More of a problem on petrols because the turbos do run red hot, literally cherry red!
Re: Simmering turbos - Dave
Stuart Bruce wrote:
>
> even if its a company
> car you can be seriously in the brown and murky if you pull
> into the m'way services just once after a hot and sweaty
> thrash and switch off immediately.

You realize you've just set me a challenge?

I'm using my Dads Volvo LPT (low pressure? Who they trying to kid ?) this weekend and if I can't cook the turbo I'm going to be gutted.

What's best, motorway at pace or just red line it in Neutral on the driveway?

;-)

Dave.
Volvo limiter. - David Woollard
Sorry Dave that won't work with a Volvo.

Start to get a bit of load on the engine for a minute and the ECU will assume you must be towing, after all no-one accelerates in a Volvo.

Then the old f-rts/towing failsafe ECU mapping will kick in and its a steady 50mph all the way from then on.

David
Re: Simmering turbos - Darcy Kitchin
Dave,
This is how I cooked my turbo. Cruising south down the A1 from Newcastle at a comfortable 90, the car an '81 Citroen CX GTi turbo, the time autumn '91 or '92. Suddenly the engine cut out as though I'd switched it off. Then it came back, faded and came back again. It was twilight, drizzling and road works approaching. Valour said try and make the 100 miles home, discretion said stop now and don't be an accident in the road works, so I put the hazards on and pulled over. The engine ticked over perfectly, but would only occasionally deliver any power.
The breakdown man arrived within minutes, as though he'd been tailing me. He lifted the bonnet and visibly shuddered. He checked for loose connections and then readily admitted defeat. It turned out later that the flywheel sensor had failed and the engine was running in fail-safe mode.
Because I knew best (don't we all?), I volunteered to drive the car up the ramp onto the back of the breakdown truck. On the third attempt of revving up and slipping the clutch I managed to get it parked on the truck. So the car was at an angle of maybe 20 degrees facing uphill and I'd just seen 4K on the rev counter. If I hadn't been shaking so much, I might have thought a little, but I didn't, and killed the engine immediately, and the turbo, obviously. Silly me.
:-(
Re: Simmering turbos - Gwyn Parry
Define simmering -- never owned a turbo, but the next one will be.
Cheers
Re: Simmering turbos - Gwyn Parry
Hey thanks for that.............................I'm glad I asked...Just one point on the Volvo's ECU/Mapping, this now explains to me why when I see a BOF driving one the indicators are never, apparantly, used. Obviously the Volvo's computer is so bright it automatically overirdes the indicators in case the flashing lights confuse the BOF......
Re: Flushing oil - Andrew Moorey (Tune-Up Ltd.)
No quick answer here but here goes. Firstly if you know the vehicles' history and you are changing the oil regularly, using an engine flush helps to rid the crankcase of contaminants and help the engine drain completely. If the car is an abused old dog serviced only when it has stopped I personally wouldn't use a flush for the reasons outlined by HJ. I would only use flushing oil to clear a problem, i.e. sticking valves or piston rings, especially on Zetec, and Ecotecs.
The small amount of overfilling shouldn't be a problem as most flushes are 250 - 325 ml but if you are nervous just unscrew the filter, let it drain and refit it, its contents should give you the drop in level you need.
Re: Flushing oil - David Lacey
We use a flushing additive (Wynns) at every oil-change service and fingers crossed, have not had another oh-god-it's-another-exhaust-valve-sticking to date.
We don't use it in highish mileage cars as it can dislodge 'gunk' etc as previously stated and can wash away various varnishes & carbon etc that keep a high mileage motor happy.
Most cars we service are marginally low on oil so these add before drain additives we use do not adversely affect the engine.
Re: Melting turbos - Stuart Bruce
Red line it on the driveway? are you by any chance related to the MOT tester who did my last diesel? ;-) or maybe that should be :-(

The engine has to be working ie you have to DRIVE it, (drive is in caps cos I mean really give it some welly) but it does get a bit difficult if the turbo is also oil/water cooled. Not sure what is the case on Volvo's, but if you cannot get some part of it glowing, you're not trying hard enough! Now there's a challenge.

BTW this is getting silly!
 

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