Hi folks, couple of questions ....

3lt auto sedan with 172k on the clock.

Two oil changes ago I replaced the ISC and found a big difference in the smoothness of the engine at idle and in gear at lights etc. Pretty happy.

Since then and the two subsequent oil changes the car has used from 3/4 up the dip stick markers to the bottom mark when before that it used virtually no oil over 7500 kms which is my oil change interval. I use Castrol Magnatec and change the filter every oil change.

I had a good look around and noticed a fairly wet rear of the engine and it appears to be coming from the rear rocker cover. Hardly enough to be the entire cause I'm guessing but wondering if anyone here has any ideas or theories over the changing of the ISC.

I will order two rocker gaskets. Is it worth getting the injectors serviced while I have the inlet manifold off? They are untouched from new.

With regards to the ISC change I found the throttle area directly where the ISC sits to be pretty grotty with oil residue from blowby/fumes etc. Is that to be expected?

Thanks

Rocker cover gaskets can leak a lot of oil over 7500km, depending on how worn they are.

Also replace your plug tube seals.

As for the rest, to me its expected - engine's dont stay perfectly clean forever.

Shouldn't be burning oil - my 3.0L auto uses no oil at 235,000 Km so it must be a leak. Check the crankcase ventilation system on both rocker covers for blockage - often oil gets pumped out the gaskets because of pressure build up.
PS. Changing the ISC is not related to this problem.

Depends on the service history and abuse the engine has received from previous owners. My engine has done nearley 300000kms and doesn't burn oil. But I've heard of engines burning with 1/3 that many kms. So U can't really compare engines. Check your exhaust for blueish smoke and while under engine load. Look under your car for wet spots between engine and gearbox, or around sump and oil filter

Sounds just like my 3L, leaks at the rear rocker cover, and drips onto the exhaust causing smoke to come out of the bonnet when i pull up. More so after a steep hill climb...
Its a common problem apparently.
As for the injectors, my mechanic (a magna nut) reckons if it is running smooth and is good on fuel just leave them, he said he's changed them before on magna's and they've started using more fuel then before!

Change all spark plugs when doing the rocker covers...

Thanks folks, will get onto those rocker cover gaskets asap.

It's been a fab engine/vehicle and been in the family since new so it certainly hasn't been abused.

I did think the injectors needed doing till I changed the ISC and now it idles well. Once in a blue moon prior it would stall at the lights.

Hi,
Get rid of the Castrol rubbish and use Penrite HPR15 to start with.

Now, get under the car and have a good look for leaks, if you are able to eliminate this then move on

Have the car at op temp, idle for 5 mins and give a couple of good revs, look behind to see if you have any smoke.

If this is negative as well then it starts to get intriging

Check these items and if no go I will keep an eye on this post