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[Omegatoy]

A friend of mine rides a trials bike. He has been advised by other trials riders to drain the oil from his bike, then fill with the correct amount of DIESEL fuel run for a few minutes making sure not to rev/load the engine.

When he told me about this I was very sceptical.

Oh yes engine has to be hot through out the operation

What do think ?

used to do that on me rover v8 every other oil change, it ran to 280k befor i sold it, never had a problem with oil pressure or cam wear through blocked oilways, its an old trick as diesel is detergent so ceans the internals!!

[Ghost]

A friend of mine rides a trials bike. He has been advised by other trials riders to drain the oil from his bike, then fill with the correct amount of DIESEL fuel run for a few minutes making sure not to rev/load the engine.

When he told me about this I was very sceptical.

Oh yes engine has to be hot through out the operation

What do think ?

DANGER  If you want to blow yourself and the car up then you can try it. But diesel burns under Presure so if you put that amount in your engine and start it I would not like to be in the near.
there is a lot of presure in the engine when running so dont do it.

[Andy B]

....
DANGER  If you want to blow yourself and the car up then you can try it. But diesel burns under Presure so if you put that amount in your engine and start it I would not like to be in the near.
there is a lot of presure in the engine when running so dont do it.

You'll need more than crank case pressure to ignite diesel.  :-?

[Grrrrrr]

I used engine flush in an old Astra engine I swapped over. The engine was pretty manky so I figured: what's to lose? Never again. Stripped everything out but it was an old engine and half of what it stripped out was the only thing holding the compression up. Smoked afterwards and was never the same.

If it has had regular oil changes then I'd just do a few extra changes at 1k intervals and leave it at that.

[Grrrrrr]

Oh, and I've heard the diesel trick performed with parafin too. However, the guy's a tinkerer and has lost more than his fair share of engines. Based on his track record alone I'd give that one a miss.

[Sixstring]

This is interesting.....as an engineer of some 30 years experience, my mentors always told me that on an engine with little or no service history, add flush to the oil and run for a MAX of 10 miles, then drain the oil when hot, leaving the car to drain for at least an hour, then change filter and refil with quality oil. the next oil change should then be HALF the distance recommended, and then as service shedule thereafter, for V6 petrol engines no more than 6k, and diesel engines 4k between oil changes.

By the way, this is advice from VX luton..............

Comments please??

[Grrrrrr]

Well I'm no mechanic so you could be right. I'm just going off my one experience - hardly a decent sample size for any statisticians out there.

I'd guess it depends on the mileage though. I got the engine off the scrappy and it was so coked up you wouldn't believe. I was scooping crud out with my fingers at one point.

Maybe engines that have done lower mileages are still pretty tight so the flush doesn't have such a big effect?

[Psychoca]

I run my oil changes far too long and notice a drastic performance increase after the oil change...

In my opinion, after the change, let your engine run on tickover for a while, with no load and let the oil flow its circuit, it will catch its own crap...

The concept of oil flush has always concerned me, hence never running it...

[Entwood]

bit long .. but the whole article is worth a read IMHO

http://www.carbibles.com/engineoil_bible.html

Flushing oils

These are special compound oils that are very, very thin. They almost have the consistency of tap water when cold as well as hot. Typically they are 0W/20 oils. Don't ever drive with these oils in your engine - it won't last. (Caveat : some hybrid vehicles now require 0W20, so if you're a hybrid driver, check your owner's manual). Their purpose is for cleaning out all the gunk which builds up inside an engine. Note that Mobil1 0W40 is okay, because the '40' denotes that it's actually thick enough at temperature to work. 0W20 just doesn't get that viscous!
Do I need a flushing oil?

Unless there's something seriously wrong with your engine, like you've filled it with milk or shampoo, you really ought never to need a flushing oil. If you're transitioning from a mineral oil to a synthetic oil, likewise you probably don't need to flush the engine first.
If you do decide to do an oil flush, first drain your engine of all it's oil, but leave the old oil filter in place. Next fill it up with flushing oil and run it at a fast idle for about 20 minutes. Finally, drain all this off (and marvel at the crap that comes out with it), replace the oil filter, refill with a good synthetic oil and voila! Clean engine.
Of course, like most things nowadays, there's a condition attached when using flushing oils. In an old engine you really don't want to remove all the deposits. Some of these deposits help seal rings, lifters and even some of the flanges between the heads, covers, pan and the block, where the gaskets are thin. I have heard of engines with over 280,000km that worked fine, but when flushed it failed in a month because the blow-by past the scraper ring (now really clean) contaminated the oil and screwed the rod bearings.
Using Diesel oil for flushing

A question came up some time ago about using diesel-rated oils to flush out petrol engines. The idea was that because of the higher detergent levels in diesel engine oil, it might be a good cleaner / flusher for a non-diesel engine. Well most of the diesel oil specification oils can be used in old petrol engines for cleaning, but you want to use a low specification oil to ensure that you do not over clean your engine and lose compression for example. Generally speaking, an SAE 15W/40 diesel engine oil for about 500 miles might do the trick.

[SR-71 Blackbird]

ok the general thinking seems to be that if the engine is already cleanish then doing a flush could cause soooo many more problems then it could have advantages. this brings me to my next question, how do i know if my engine is clean inside, bit of info on her, shes had very regular oil changes according to the log book and i got her 6700 miles ago and i changed the oil straight away when i got her and then again after another 4000ish or so. Are there any techniques or tips to find out if she is nice and clean inside? i have looked under the oil cap and it seems very nice and clean but i can only see a tiny bit og the engine and its rather large 

thanks guys, keep em coming i really value your thoughts as ive never had a turbo diesel before

[Marks DTM Calib]

Heres the issue.

By flushing you dislodge all the deposits....and some of these will clogg the oil pickup strainer....so if the engine is bad, dont do it....

Modern oils also contain detergents but, they are not nearly as aggressive as the flushes and hence offer a gentle clean. As a result, the deposits are slowly removed and generally pass through the pump and get trapped by the oil filter (they are likely to be much much smaller)....hence why we recommend short oil changes for filthy engines!

As an aside, if you have blocked oil jets, no detergent will clear them......if they are slightly clogged and the spray pattern compromised then yes, it might help. the cleaning process requires the flush to be able to pass oer the dirt....in the case of a blockage, this cant happen and hence, it wont touch it! 

[TheBoy]

On a TD, due to the oil jets, I'm with Omegatoy for obvious reasons - if I think its needs doing (high temp, yet cooling system perfect), I would do it.

It certainly sorted out the overheating on my old tractor (after replacing the engine cooling system)

[VXL V6]

What about the DTi's? I intend to change the oil every 3K for a while but just wondered on peoples thoughts on this engine.

The V6 can suffer a problem of a gummed up oil pressure relief valve if oil changes have been ignored (or the 20K change scheme was used!), this causes the pressure relief valve to not operate correctly causing an over pressure situation which will cause oil to leak past the camcover seals no matter how many times you replace them and clean the breathers. The moral of the story is to change the oil regularly!

[TheBoy]

What about the DTi's? I intend to change the oil every 3K for a while but just wondered on peoples thoughts on this engine.

The V6 can suffer a problem of a gummed up oil pressure relief valve if oil changes have been ignored (or the 20K change scheme was used!), this causes the pressure relief valve to not operate correctly causing an over pressure situation which will cause oil to leak past the camcover seals no matter how many times you replace them and clean the breathers. The moral of the story is to change the oil regularly!

I guess same applies, if no problems, just stick to regular oil changes

With my tractor, quick oil changes were not curing the issue I had, hence tried the flush on Omegatoy's advice, which worked for me

[Marks DTM Calib]

What about the DTi's? I intend to change the oil every 3K for a while but just wondered on peoples thoughts on this engine.

The V6 can suffer a problem of a gummed up oil pressure relief valve if oil changes have been ignored (or the 20K change scheme was used!), this causes the pressure relief valve to not operate correctly causing an over pressure situation which will cause oil to leak past the camcover seals no matter how many times you replace them and clean the breathers. The moral of the story is to change the oil regularly!

Nah.....if the presure relief valve was to stick shut it would give a higher pressure oil system....this would not affect the cam covers as they are at crank case pressure....it could affect cam and cranks eals if they get flooded with oil and have blocked drains on them