Engine flush and gunge dissolving power

[charentejohn]

Just done an oil change on my poor old Transit and noticed the state of the oil compared with flushed oil on the Xantia. Whether you do or don't like flushes they do seem to work and I have the photos to prove it. I thought I would describe them though but if you need proof I have it.

I was impressed with the Forte flush I did a while ago as I drained the oil into my usual 20L container with the top cut off. This was really bad having old oil left on the side from previous use with a similar consistency to tar.
After draining the oil into it then decanting into an old oil can the interior of the 20L container was (nearly) spotless. Some lumpy bits on the bottom but it generally came up clean. So basically the drained oil with flushing additive also dissolved the gunge on the container, it was in there for 20 mins.

I mention this because when I did the transit and poured off the oil the container had a 'tide mark' where the oil level was. So basically it was 'stickier' then the flushed oil. So flushing does do something.

Not sure if there is a difference in the action of a flushing additive or flushing oil in this respect. I guess the flushing oil is thin so washes out gunge, whereas an additive type flush additive dissolves it into the existing oil. This would explain why it dissolved the old oil in the container.

I have used flushing oil twice in the past but think I will stick with additive types in future. The continuing action of the additive also would explain why the new oil after the flush turned black instantly (gunge still dissolving) so then I replaced that oil the new oil is still only a bit browner than normal after 800miles or so. I assume my next flush in about 5k miles won't do the same as all gunge should be gone and it will remove only new stuff, and any bits it missed first time.

[Rhothgar]

A friend of mine who has an automotive garage absolutely swears by Forte. It is a lot more expensive than most flushes, if not the most expensive.

I used it in my Xantia a while back. Unfortunately, with older diesel i.e. non-Hdi, it is apparently impossible to achieve clean oil. Possibly if you did a flush, new oil, another flush immediately and new oil again would it clarify the oil. Hard to say. It might even take 3 attempts all in one session. That's a lot of wasted oil and flush though.

I find it mildly irritating that on a Series 1 Xantia, the oil starts getting dark immediately.

True solution is a full engine strip down. Professional decoke by an engineer's shop so everything is as new and rebuild. I'll let you know as I am intending to rebuild a Xantia engine this year.

[charentejohn]

A rebuild is the ultimate solution and flushing can be a long term process I think.
After the first flush the new oil turned black immediately, I stood it for a while then had to change it as it was bothering me.
So far fairly clean but starting to cloud up, still that seems reasonable as engine has 135k on the clock.

I did the first flush with engine ticking over for 40 mins as recommended for first time, but I think the engine was so bunged up it hadn't broken down all gunge. So the new oil ended up with the remaining gunge in it quite quickly.

Next two flushes planned at regular oil change intervals. I seem to recall they recommended 20 mins on tickover for engines regularly flushed, so I will do another 40 minute one then perhaps 25 mins from then on.
I know some people drive carefully for a while with the additives in, rather than leave on tickover, and report no problems. Having seen what it removes I will stick with the tickover method though.

[Ratheram]

Where I work, we are on the good garage scheme and have to use Forte additives and flushes. They are expensive yes, but you do notice a difference and the customers seem to notice it too. We are recomended not to drive with the flushes in as, it isnt oil so it doesnt lubricate like oil does and can cause wear under load. Its ment to be the best with minimum wear under idle but the rep told us that...

The modern HDi engines, 1.4hdi, 1.6hdi, 2.0 16v hdi and that, you flush the engine out, drain it out like normal, let it drip for a while, change oil filter and, if its got the option, drain the housing, put new fully synthetic oil in it, run it for a little bit, check the oil, its black. Always the same. if its done 40k miles to 200k miles. Dont know why.

[Citroenmad]

Interesting thoughts, I agree that flushing can take a few goes before you notice clean oil after an engine run, espcially if the oil changes have been neglected.

I find the HDis respond well to flushes, if its one which has only had the routine 12500 mile services then it does take a few flushes to get it clean. However if it has had 6000 mile services throughout its life then the oil becomes clean straight away and can stay clean for well over 1000 miles.

I use Forte in all our cars and it does a very good job, though the XUDs do get dirty oil quickly no matter how many flushes they have had.

It might not be the norm thing to drive the car with the Forte flush in the engine, however it can be recommended in some cases and its not advised against. I believe even the Forte tech helpline will recommend it for certain problems, sticking lifters etc.

Personally I always drive the car with it in and have never had any issues as a result and have done so with many different cars. I usually warm the engine up and drive about 5-10 miles and then drain the oil on my return. At one point our 2.0HDi 206 had a forte flush in for about 2 days (200-300 miles!), that was a couple of years back and no ill effects came of it ...

My dad is a Forte rep ... At one point the Forte reps were sent around a 'rig' which tested the lubrication of oils by running the oil between a spinning small metal wheel and a static metal plate. The force at which the two could be changed by adding or taking off weights. We got a few different flushing agents and did the test on a number of them. All but one of those wore out the metal wheel in no time, generating a lot of heat. They varied as to how much weight needed to be added before the metal bearing was scored (noticable as it sounded rough) and by far the highest weight needed to be used to wear out the bearing was with Forte flush, as it is high in lubricating factors, unlike many other flushes. Some im sure you would just be doing the same job if you poured in net petrol, some 'iffy' garages do I believe.

The problem when using a flush (id not recommend anything other than forte as ive only the above experience with them) is to use it on a car which has really been neglected in terms of missed servicing. Flushing a car which has had the same oil for 20-30+K miles would be risky as it will dislodge grime and could potentially block oil strains and feed pipes. In this case its recommended to do an oil and filter change, then with this new oil put in the flush and run it for a short period, then to drain the oil and replace the filter again.

Also in some engines, not many, its recommended that no flushes are used. The VAG 1.8 20v engines have this recommendation due to a very fine gauge on the oil strain which is very easily blocked. A similar storey is also on the 1.6HDi which again has a fine oil strainer to the turbo. However with the 1.6HDi engine servicing can be every 20K miles (far too long imo) and so it has a good opportunity to get very grimey. Stick to much shorter service intervals and the 1.6HDi is actually a very good and reliable unit, stick to the long service intervals or even forget about them and you will soon run into problems. A family member has just experienced this on her 407 1.6 and its eaten the turbo.

I serviced a C4 1.6HDi which had not been serviced for around 30K miles and two years. The oil was very odd looking, it didn't even feel slippery between my fingers, it felt dry and could not have been any more dirty. I did actually flush this one but only ran it for around 10-15 minutes. I then replaced the oil with the correct Total ECS and fitted a genuine filter to it and sent it off with its owner. I asked if he would bring it back about a month later and I would do it again, he did and the car got a 20 mile flush and I replaced the oil with the correct stuff and filter again. It was alsmot golden after a small run but ideally needed another flush. Needs to be a slow process if its a neglected engine. Sadly its now gone for 2.5 years and 35K miles without a service, I can't understand how it still goes as after all it is a 1.6HDi which need regular servicing. This engine is certainly a case of the 20K mile manufacturer recommended service intervals being too long and their reputation is paying for it. The worst I have heard of is the Audi A2 1.4TDi wich is supposed to go 30K miles between services, I can't quite believe this. Ive had a few cars with that engine and I used the same oil as is recommended on the A2 but it only had 10K miles service intervals ...

If you change your oil every few thousand miles then its probably pointless in doing engine flushes. I do mine roughly every 6000 miles and do use a flush, but its personal opinion. Despite what im about to say, I couldn't care less is no one bought Forte products, but why put clean oil into a dirty engine?

The above is my personal experience and not gospel

[charentejohn]

Thanks for the info, and more importantly the warnings.
I think my engine has had regular oil changes but not certain how many miles they were done at, about 10k would be a worst case guess. Main problem in my engine was lack of a thermostat for a while (no idea how long) so always running cold in winter so I would assume a lot of sludge buildup as oil not heating up correctly for many months.

I have only used flushing oil before nd the Forte is the only additive type flush I have used, it has a good reputation and worked very well so I will stick with it. Others may be as good but why change if I know it works.

The suggestion to change the oil, run for a short time then add a flush sounds resaonable. I think I ended up doing the same thing in reverse, flused the original oil, saw the new oil went black too quickly, then replaced it. Having seen the gunge dislodged after the first flush I can well believe dislodging a lot of built up gunge (20k mls+) could cause a problem.

I think I will do another flush at 6k miles just to make sure I have removed all I can, I should be down to the final bits by now. The leave it to every other change at 12k miles, about 2 years in my case.

[Ratheram]

My dad is a Forte rep ... At one point the Forte reps were sent around a 'rig' which tested the lubrication of oils by running the oil between a spinning small metal wheel and a static metal plate. The force at which the two could be changed by adding or taking off weights. We got a few different flushing agents and did the test on a number of them. All but one of those wore out the metal wheel in no time, generating a lot of heat. They varied as to how much weight needed to be added before the metal bearing was scored (noticable as it sounded rough) and by far the highest weight needed to be used to wear out the bearing was with Forte flush, as it is high in lubricating factors, unlike many other flushes. Some im sure you would just be doing the same job if you poured in net petrol, some 'iffy' garages do I believe.

Our forte rep came round work 1 day to top up our Wurth rack with Forte products to find that the Wurth rep beat him and filled the Wurth rack up. We got a lecture how in a test rig, forte flushes can take 6 weights. He got sarcasm. Couldnt explain anything, just been told that other flushes could barely take 1 weight. 1 of them, "okkayyy, sales tactic failled, what next are you going to come up with?"

And yes, high milage Audi A4 1.8T... flushed oil out, fine. 20,000miles later, flushed oil out, fine. 4,000miles later, no oil pressure

[Lighty]

We use Forte flush in the workshop, bu I certainly don't use it on every job due to cost.
I believe it is valuable on the 1.6 hdi units, as oil starvation is so common. These engines pollute themselves with dirty exhaust gases through the egr system. We have a C3 hdi with 300,000 miles on its clock, it had the egr blocked of at about 70k, and it is the cleanest , sweetest running engine you ever would see, spotless inside the oil filler cap.
The oil strainer in the sump blocks up on the 1.4 & 1.6 hdi unit, but the oil feed pipe to the turbo has a small gauze pushed inside it, this regularly blocks and starves the turbo of oil, add to this the heat build up from a blocked dpf,and you have a fried turbo in no time. We always remove the gauze in the pipe when replacing a turbo, dirty oil is better than no oil in my book.

[Peter.N.]

I agree with Chris, if you do more regular oil changes than specified not only will it probably not need flushing but it will considerably lessen the chances of major problems such as turbo failure.

Peter

[charentejohn]

I will definetely be changing the oil at 6k miles in future, especially considering the miles on the engine but will do one more flush just to be sure.
If the engine is in good condition generally then a flush should not hurt it as just removing unwanted gunge which shouldn't be there in the first place. If it is in poor condition then I can see how 'gunge overload' in the oil could cause a problem, I was certain the black oil I had was not normal black oil which is why I dumped it asap.

Good point to warn of small gauge filters in the 1.4/1.6 HDIs blocking though. Is there a rough idea of when not to flush these engines, I assume ok if regularly serviced and if oil looks ok in general.
I ask as I am looking to buy a C3 with a 1.4HDI and would want to run a flush through just to start it's life with me 'clean' as it can be. I should be able to find one here with less than 80k miles, I hope. Probaly worth doing the, oil change, add flush, oil change again scenario just to be sure, oil is cheaper than engines

[addo]

Our forte rep came round work 1 day to top up our Wurth rack with Forte products to find that the Wurth rep beat him and filled the Wurth rack up.

Lets see Forte come up with a competitor for CU800, or the handy boxes of rubber hose plugs/caps.

Wurth have a global presence; Forte can't be arsed representing themselves here. I reckon that says a lot (complacency). If I could buy their coolant additive at equivalent to the UK price, I would. However I am not going to pay silly money for something we still debate the merits of, especially when there are local competitors in the right pricerange.