To flush or not ?

[EastPete]

Any opinions here on the pros and cons of using engine flushes when changing the oil on the CDT M47R engine ? I was thinking of doing this at next oil change (due soon), but have seen some negative comments on some forums about this being a waste of time/money, and actually doing more harm than good.
All comments welcome
Pete

[Heddy]

My 75 is due an oil change, I won't flush it because the oils used today apparently have enough additives (detergents if you like) to keep the engine clean. Can't see much benefit in flushing, but do see the benefits of halving the specified 15k interval (mines a diesel). I can buy into the fact that the old oil will collect carbon, soot, filings etc, so a regular change would be a good thing. IMHO of course

[maxi_crawf]

Every time mine goes in for a service, CDT (and MOT at the same time), they always use Fortis engine flush before they replace the oil and filter, I think it helps to get rid of as much rubbish as possible.

[rovexCDTi]

If you are concerned about using a flush you can just to use cheap new oil as a sacrificial flush. Its very easy if you have a pela pump, more of a pain if you dont.

Just suck out the old oil, 5 litres of it anyway, refill with cheap oil (that meets the spec) something like ECP QX oil thats often just £12 when on offer, less if you use 10w40 semi.

Drive for a bit, as long as you fancy, maybe 100 miles, then drain it properly, replace the filter and add your preferred oil.

[trikey]

Originally Posted by rovexCDTi

If you are concerned about using a flush you can just to use cheap new oil as a sacrificial flush. Its very easy if you have a pela pump, more of a pain if you dont.

Just suck out the old oil, 5 litres of it anyway, refill with cheap oil (that meets the spec) something like ECP QX oil thats often just £12 when on offer, less if you use 10w40 semi.

Drive for a bit, as long as you fancy, maybe 100 miles, then drain it properly, replace the filter and add your preferred oil.

That's the way I do it too

[rich17865]

My car and van are both oil changed at 5000 miles and a flush goes in each time. I am sure a build up of crud does more damage than the flushes would.

[Dorset Bob]

Unless you take everything apart, you will never change all of the oil in the system. Take the oil present in the oil cooler, for example.

The trouble is with flushing oils is that some of it must still be present after the oil change.
As a result, this must compromise the specification and performance of the new oil going in.

With modern oils, flushing is on out of date practice, IMHO.

[rich17865]

My local garage made up an advert set for the engine flush they sell while I was there one day.

Two small glass bottles, one with just used engine oil from the workshop and one with used oil and a few drops of the flush. Both half full.

Shake both, the glass with the flush in the oil is clear at the top in about 15 seconds. The one without the flush is sort of see through in about 15 minutes.

Sells it to me.

So that will be used oil from a car in the workshop, no old fashioned oil, oil with modern detergents in.

I will keep adding flush, and recommending others so the same.

[Dorset Bob]

Originally Posted by rich17865

My local garage made up an advert set for the engine flush they sell while I was there one day.

Two small glass bottles, one with just used engine oil from the workshop and one with used oil and a few drops of the flush. Both half full.

Shake both, the glass with the flush in the oil is clear at the top in about 15 seconds. The one without the flush is sort of see through in about 15 minutes.

Sells it to me.

So that will be used oil from a car in the workshop, no old fashioned oil, oil with modern detergents in.

I will keep adding flush, and recommending others so the same.

Exactly the point, a demonstration of phase separation would definitely not sell it to me.

[Mike Noc]

Originally Posted by EastPete

Any opinions here on the pros and cons of using engine flushes when changing the oil on the CDT M47R engine ? I was thinking of doing this at next oil change (due soon), but have seen some negative comments on some forums about this being a waste of time/money, and actually doing more harm than good.
All comments welcome
Pete

My M47R has had the oil changed every 15k miles from new using decent quality semi-synthetic but no flushing. It has now covered coming up to 360k miles, nothing lubricated by the engine oil has been changed and it still runs fine.

Doesn't even use any oil in between services. So I can't see how flushing would have improved things, and I'd have had to pay for 23 of them to date.

If you are unsure of the service history then maybe there could be a benefit as a one off though.