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Discussion Starter · #1 ·
Just had the P reg (99K on clock) serviced at a local garage for £100 all in.

They had a notice on the wall that said "Why put clean oil into a dirty engine? We always use an oil flush during servicing"

Well I checked the oil this moring having done a couple of hundred miles the oil is still good and clean, and on startup from cold I no longer get the 3 seconds of light rattle from the tappits before they fill up fully with oil and the engine just seems quieter and sweeter than it did before

I am not sure if oil flushes are standard during servicing but if this is anything to go by I'd recommend it.

Steve
 

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Standard practice at main dealer services I've had done on Merc's, BMW's and VW's.

My old man used to do it with Diesel in the old days. Swears blind it extended the life of the motor. He also advocates an oil additive which makes the oil cling to the upper engine parts to quieten start up rattles.
 

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Running synthetic oil with regular oil changes (5K), you don't necessarily need an oil flush...just let the old oil seep out gently and the engine is clean as a whistle![/b]
Agreed!
An engine flush should not be necessary unless oil change intervals have been exceeded and/or poor quality oil has been used.

A flush often resolves tappet noise problems (where hydraulic tappets are fitted), by clearing out gunk whhich has restricted oilways and reduces oil pressure at tappets - especially on start up.

But there are dangers!
Some manufacturers (Renault, etc) specifically state in user guide NOT to use an engine flush.

Why?

If enough gunk has built up, radically loosening it can cause oil ways to block up, reducing lubrication and exagerating wear!
 

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I'd heed Pauls warning!
I have just cleaned out the sump, oil pump etc on a reasonable high mileage engine (around 60k miles? not a Saab!) that had obviously never been flushed out before. There was a awful lot of rubbish stuck to the sump, pickup strainer and oilways that I would really rather not have loosened up and floating around in my engine! Of course, if you have always used a flush then you won't have sludge building up so it is probably worth continuing unless you think the oil will do the same job.
 

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Surely, altho a little expensive, 2 x oil change & filter and 2 x oil changes a year for a couple of years would prob reduce the sludge a bit. But flushing has been advised to me. I run semi/synth and it was said to change to full/synth I would have to flush.
 

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it was said to change to full/synth I would have to flush.  [/b]
I wonder why that was said?

It implies that adding a flushing agent removes more of the old oil. And it also implies that any remaining oil, mixed with flush, is better than just old oil remaining.

I would have thought that provided the oil was suitably warm, and the car was left to drain for a good 10 minutes (Some oils recommend draining old oil for at least this time), virtually all the old oil will be removed anyway, without the need for a flush.

Bearing in mind that any flush added will probably remain in places like lowpressure chambers of hydraulic valves, etc, I would be reluctant to use a flush except in exceptional circumstances.
 
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