Holden Rodeo: Oil burning from blocked piston oil-ring drain holes (3.2 V6 6VD1)

The 6VD1 has only about four small drain-back holes behind the oil control ring on each piston, and as the engine ages those holes coke up with carbon. Oil then sits in the ring groove instead of draining back to the sump, gets pushed past the ring and burnt, and the engine starts using roughly a litre every thousand kilometres. Isuzu later redrilled the ring land with about ten holes, so the earliest 3.2 V6 Rodeos are the worst affected. It rarely stops the engine running, but it fouls plugs, cooks the catalytic converter and quietly runs the engine low on oil for an owner who never checks the dipstick.

• Oil level drops a litre or more between services with nothing on the driveway
• Puff of blue smoke on start-up or after a long downhill run
• Blue smoke in the mirror when you accelerate after backing off
• Sooty, oily spark plugs
• Smell of burnt oil at the exhaust

1. 1

   Pull the dipstick before the engine is started and note exactly where the level sits, because a car that is habitually run low will read well under the full mark on a cold morning.

2. 2

   Ask the seller straight out how much oil it uses between services and how often they top it up, since an honest owner of one of these will tell you.

3. 3

   Have the seller start it from cold while you stand behind the car watching the tailpipe for a blue puff, then take it for a drive that includes a long downhill with your foot off the accelerator and watch the mirror as you accelerate again.

4. 4

   Look inside the exhaust tip for wet oily black soot rather than dry grey powder.

5. 5

   Ask to see the service book and check the oil change intervals, because these engines were very often serviced late.

6. 6

   If a workshop inspection is possible: have a compression and leak-down test done on all six cylinders and have the spark plugs read for oil fouling.

Parts involved: Catalytic converter.

$4,500 to $8,000 at New Zealand independent workshop rates. That is for this job on its own, not for the car.

An estimate, in NZD, for the repair as normally carried out. What a specific car costs depends on which part has failed and what it damaged on the way — treat this as the floor for a negotiation, not a quote.

• “How much oil does it use between services?”
• “How often do you top the oil up, and with what?”
• “Has the engine ever been rebuilt or had new rings?”
• “Were the spark plugs oily when they were last changed?”

The failure described above is documented in the sources below. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them.

• MyMotorList Isuzu 6VD1 engine profile - oil consumption caused by too few piston oil drain-back holes
• PlanetIsuzoo Isuzu SUV Forum thread '6VD1 what typically goes wrong on them?'
• BobIsTheOilGuy forum thread 'Isuzu Rodeo Oil Consumption'
• PlanetIsuzoo thread '6VE1 3.5L oil consumption fix while rebuilding' - revised piston ring drain-hole count