Engine sludge

Nitrojan · 25 Mar 2012 at 18:31

What is the best way to clean an engine as a result of neglecting oil changes? A friend of mine has missed a few services and after realising the consequences of not changing the oil, is (rightfully) becoming paranoid.

I have done a little reading into it, and from what I can see, it is advised not to use any kind of 'oil flush' solvent and instead, simply either remove the valve cover and inspect the engine condition.. or buy cheap value oil of the same grade, run the car for 20 minutes before draining and replacing with a good quality oil.

What else can be done? My knowledge is limited, so hopefully someone could offer some additional advice

Simon · 25 Mar 2012 at 18:34

Best bet is a fresh oil change and run that for a bit to clean it up, then put the proper oil in with the new filter.

If its easy - worth taking the valve covers off and have a look.

What car is it?

Nitrojan · 25 Mar 2012 at 18:37

Simon said:
Best bet is a fresh oil change and run that for a bit to clean it up, then put the proper oil in with the new filter.

Yeah this is what I suggested also - thanks

The car is a 2003 BMW 325 - not sure how easy it would be to remove the valve cover but I heard that this was an option.

Nitrojan · 25 Mar 2012 at 18:46

I have also read of adding 2l of ATF along with the next oil change, and not running the car hard for 100 miles or so before re-draining?

Does this sound completely bonkers, or would it work without risking killing the engine?

aproctor · 25 Mar 2012 at 18:48

Nitrojan said:
I have also read of adding 2l of ATF along with the next oil change, and not running the car hard for 100 miles or so before re-draining?

Does this sound completely bonkers, or would it work without risking killing the engine?

ATF is just thin oil and would treat it like an engine flush.

Nitrojan · 25 Mar 2012 at 18:50

aproctor said:
ATF is just thin oil and would treat it like an engine flush.

Ahh that makes sense - so I guess just use cheap oil and do multiple flushes is the best option before replacing with premium stuff?

The car has always used fully-synthetic, would this be of any advantage as to the likliness of engine sludge forming?

TaKeN · 25 Mar 2012 at 19:06

Personally, I wouldn't worry about the 'sludge'.

Just get it hot, drain it. New filter and oil then see how it's looking after a few miles.

Sticking ATF just stinks of bad idea IMO. Just out of interest.. how do you know there's sludge in there? It's just very dirty oil surely?

Nitrojan · 25 Mar 2012 at 19:10

TaKeN said:
Personally, I wouldn't worry about the 'sludge'.

Just get it hot, drain it. New filter and oil then see how it's looking after a few miles.

Sticking ATF just stinks of bad idea IMO. Just out of interest.. how do you know there's sludge in there? It's just very dirty oil surely?

Very dirty oil yeah and dirty when looking into the oil filler cap. Yeah personally, I wouldn't use any ATF or 'flush' fluids - but just wondering what the general recommendation is

acemastr · 25 Mar 2012 at 19:13

Mines the same under the Oil cap, going to be simply replacing the oil and filter soonish

[TW]Fox · 25 Mar 2012 at 19:20

How many miles since it was last serviced?

Nitrojan · 25 Mar 2012 at 20:19

[TW]Fox;21552096 said:
How many miles since it was last serviced?

17,000 miles (approx) :eek:

Simon · 25 Mar 2012 at 20:20

Fine. My girlfriend Clio hasn't had oil changed in 25k miles

Brookert · 25 Mar 2012 at 20:22

I would replace the oil and filter, give it the italian service a few times, then do another oil and filter change.

If you get the oil hot, you can ensure and sludge/junk is resuspended in the oil, and safely filtered or drained away.

Minstadave · 25 Mar 2012 at 20:22

Nitrojan said:
15,000 - 20,000 miles

That's not catastrophic, a lot of cars on long life services go 14-16k between changes. I'd just change the oil and filter ASAP and if it's still looking pretty horrible after the change do another change after a few thousand miles.

Make sure you rag it around a bit to get the oil hot before each change.

Nitrojan · 25 Mar 2012 at 20:30

Minstadave said:
That's not catastrophic, a lot of cars on long life services go 14-16k between changes. I'd just change the oil and filter ASAP and if it's still looking pretty horrible after the change do another change after a few thousand miles.

Make sure you rag it around a bit to get the oil hot before each change.

Thanks for the input guys!

Brookert said:
I would replace the oil and filter, give it the italian service a few times, then do another oil and filter change.

If you get the oil hot, you can ensure and sludge/junk is resuspended in the oil, and safely filtered or drained away.

Forgive me for maybe sounding stupid, but what do you mean by the italian service?

TaKeN · 25 Mar 2012 at 20:40

Italian Service/Tune up.

Thrash the life out of it in other words

[TW]Fox · 25 Mar 2012 at 20:52

Nitrojan said:
17,000 miles (approx)

Errr you do realise the 325i has variable servicing? They can go up to 20k between services quite legitimately :confused:

Nitrojan · 25 Mar 2012 at 20:57

[TW]Fox;21552656 said:
Errr you do realise the 325i has variable servicing? They can go up to 20k between services quite legitimately

Didn't know this! Is this the same for most BMW's or specific models?

Matt82 · 25 Mar 2012 at 21:20

regarding the atf trick, i have done that on my old golf (95, 235k miles) years back to quieten down a couple hydraulic lifters.

it ended up quietening them all down. mine are quieter than equivalent engines on half the miles

[TW]Fox · 25 Mar 2012 at 21:24

Nitrojan said:
Didn't know this! Is this the same for most BMW's or specific models?

It is the same for most BMW's. The 325i has an M54 six cylinder engine. This is the same engine (though smaller) that I have in my 530i which in the hands of its original owner regularly went almost 20k miles between services. In my hands due to my much lower mileage I tend to go about 12-14k between services.

The car tells you how many miles until the next service when you turn the engine on.