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MG MGF Technical - Oil Flush, Good Or Bad??

Does anybody have any thoughts on the use of Flushing Oil During a Service??
Is there a Danger of any Removed 'Crud' sticking in an Oil Gallery for example??

If you are not sure of the history of the engine I'd flush it but get a garage to do it for you.
Did ours after we purchased the car the result was a lower oil temperature and quieter hydraulic lifters. I did another oil and filter change at half the recommended mileage just in case there was some left over crud floating around.
Dennis Montgomery

Flushing oils are good and as long as the correct procedure is followed can only help your engines life

ALWAYS USE a well known brand and DO NOT USE ADDITIVES - EVER!

Always use a well know quality oil - Castrol / Mobil ETC ETC


I think that flushing oil has its uses, but possibly a well-maintained modern engine using quality oils and filters isn't one of them.

I used this stuff on my 1.8 at around 13K when the engine had a hydraulic tappet rattle. I used Forte Engine Flush as it was advertised by my dealer and apparently used by them as standard on routine servicing, and also had other complimentary comments. The stuff stinks like engineers cutting oil (down, Dieter) and is not very pleasant. I refilled with Castrol Magnatec, another nosiy tappet cure, but to no avail and the complete set of tappets was replaced. Now I'm back on Mobil 1 with silent tappets.

At the time I was a little desperate to fix the tappet noise. I would not normally dream of using flushing oil, for a couple of reasons. I am very averse to putting anything into the oil, even for the 10 minutes on tickover that flushing oil requires. Also I do not believe that a modern engine run on quality oils and filters that are changed regularly would ever require such stuff. There are enough detergents and dispersal aditives in current oils to keep the engine internals quite clean over extended periods. When I lifted the head on my 214 - yes, HGF - at 60k miles, the latter half of those run on Mobil 1, it was as clean as a whistle. Oily, but clean.

So if you're on your original filter and you use the cheapest oil on offer at the local garden centre then flushing oil might be a good idea. But if you kiss your car goodnight, as I guess you do, then I wouldn't bother.

Regards, Kes.

Good IMHO - particularly for older higher mileage cars like my MG Montegos. The muck the "wynns" shifted was surprising. Soon after "flushing" I grounded two sumps leaving minute splits near the drain plugs which meant small leaks so both sumps had to come off for repair. I was amazed just how clear and clean those sumps were inside. Unlike on a few previous occasions when I removed car sumps without prior flush treatment, there was nowhere near the quantity of thick muck adhering to just about everywhere inside the engine. I was impressed.
John McFeely

Mark, engine flushes can be very beneficial, however, I recommend properly following directions on the bottle and being especially carefull about using it in high mileage engines that have a lot of sludge built up over the years. This year I have repaired 5 cars that suddenly lost oil pressure because of the incompletely disolved sludge/muck that gets trapped in the pick up screen. There is little concern if the engine has been reasonably or moderately maintained, but for engines with alot of hardened sludge, recommend removing valve covers and oil pan to manually clean.

Modern oils have the ability to keep sludge in suspension so I suggest that flushing has little value and a certain risk. If in doubt about what oil a previous owner has used. Change the oil and filter using your preferred oil, drive a few hundred miles and change them again.


IMHO - Problem is servicing is getting longer between changes so as oils progress manufacturers push limits further

I read a report on motorcycle oils that said that many of the lubricant qualities of oils including synthetics were lost by 1000 miles (service intervals on bikes are usually 3000 miles)

Also cars with hydraulic tappets have very slim oil feeds/gallerys - easily blocked

So in my opinion change the oil every 5000(rather than 10000) miles and flush at every main service

For the sake of 30 odd every 5000 its the most important part in your engine!!!

Also keep the extra reciepts - its a very good selling point (private sales)

Modern oils should not need an oil flush. No high mile experience with my MG however have been running a 1.6 CVH Ford Fiesta for the last 10 years, 170,000 miles. oil changed every 6K miles with Motorcraft API/SG oil approx 6 per 5 litres. The engine has no trace of black sludge under the cam cover (these engines were particularly prone to the black death). The engine is the only part of the car willing to go on forever. I would just recommend regular oil and filter changes and so long as the oil is API/SH or higher you don't need to spend a fortune on it either.If I had used Mobil 1 on this car it would have easily cost the price of a new engine over this milage
Paul Robertson

As I said earlier in this thread I think flushing IS beneficial for some engines for a number of reasons. My experience is with older, higher mileage cars of 10 or more years. Things may be different with more recent engines.

Couple of visual benefits to report:

After a flush and filter change, the fresh oils appear to retain their original colour much longer before becoming discoloured. I've noticed this with both my wife's 1990 Montego 1.6LX and my EFi and Turbo cars. Surely a positive sign.

When repairing the two sumps on my 2 litre Montegos, unlike my experience with other car sumps, the insides were surprisingly clean despite 120 and 140 thousand miles respectively.

Replaced those moulded camshaft cover gaskets on the 1.6 engine recently at 110,000 miles. They'd become hard with age and were starting to weep small quantities of oil. This was the first time the cam covers had been removed in the 11 years we've had the car. They were also very clean inside as was the oil which collects there too. Similar cambox covers removed on old cars at breakers show much build up of old oil crud and filthy oil.

Impossible for me to measure but older engines actually "feel" better following the first one or two flushes and oil changes.

I dont think it's a "placebo" effect ..... :-)

Anyone know just how big is the risk of dislodged old oil crud fouling an oilway or is that really a very remote possibility?
John McFeely

Thanks for the Comments...

This thread was discussed between 07/01/2002 and 14/01/2002

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