30,000kms without an oil change

Jun 3, 2016
South OZ
I changed the front valve cover on the Kluger (2005 Toyota Highlander).

Found this nice surprise. I have always changed oil every 7,000kms since getting the car at 160,000kms. It now has 220,000kms. No issues apart from a fouled front spark plug due to spark plug tube seals leaking.

I noticed that the previous owners had a mysterious section in the service history missing at around 100k, where they put over 30,000 kms on the engine with no service records.

Looks to me like they just didn't service it. Would conventional/semi syn oil for almost two years and 30,0000kms cause this?

I put some engine flush in after cleaning as much crud off as I could. Dumped oil after the flush. Hasn't blown up yet.
vcg kluger.jpg
regular 30k km oil changes on group1/2 oil with a moderately challenging engine like the toyota mz v6? sure

oil does very little sludge cleanup so it’s been there for a long time
2004 Toyota Sienna 3.3 here, similar observation here, not as much, but the other side only half as bad. I vacuumed out some larger chunks and cleaned up the valve cover some, going to leave the rest to short change intervals.

Back side is where the PCV valve resides, change or clean it or I'd even consider driving without one if it looked as bad as this PCV valve did when I bought it.

I'm thinking the front bank is more vertical and prone to sludge build up because of the heat.
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A couple things,
1) You never know, previous owner could have went to a quick oil change place and not documented it.
2) Or,
You said 30k kilometers, which
is slightly less than 20k miles…I did once per year (20k miles) on a 2005 Honda Accord for many years…higher end oils and filters, but definitely doable.
I think with a good synthetic + filter and highway driving, 30k kms would be ok. But city driving over a couple years with average oil in hot Australian summers? Apart from this one missing part, the service history has been good enough to prevent sludge I would think. Not many changes over 10k kms.

Engine seems to leak a bit of oil too so I wonder if they were low on oil and ran it for 30k... that might do the trick.

Nevertheless, I agree with you 2EHA, that sludge was there from the previous owners. Would need some super strong solvents to lift that off. It was gummy as hell in spots and quite dry and flaky in others! I high pressure cleaned the valve cover after de-gunking it with degreaser. I didn't go too hard on the head and just scooped out the major crap carefully where possible.
My BMW is supposed to go +/- 25,000 km between changes, that's with a good oil of course. So an engine that's easy on oil shouldn't be in that shape after 1 extended interval.

Makes you wonder if the quick change places were actually changing the oil. Or do you have a coolant into oil leak?
That’s really bad, not sure what it’d take to get it this bad, but that’s going to require manual cleaning - with hopes the sludge won’t dislodge and get into the the oil galleries when oil changes/fresh oil is introduced.
That's ugly, but rather than risk engine damage by attempting to clean it, I'd drive on and continue with your normal OCI... probably just with whatever semi syn happens to be on sale.
Dang that motors been abused. I would try to clean it up manually and use a shop vac and pick with some paper towels below to keep the bits from falling into the motor if possible.

As suggested you need a new pcv valve as well. The motor will probably keep going without issue. Cut open the oil filter on the next few oil changes to see if those bits or sludge are being cleaned up.
I'll have a look at the service history again but it only missed that one 30k kms.

I did notice that there was a new radiator in it when I purchased it years ago. I asked if it overheated at all and they said they just noticed a leak in their driveway and then their mechanic said it needed to be replaced. Maybe it did overheat.

I'm definitely going to just keep doing regular OCI and nothing special. It has gone this far with this amount of sludge already.... every extra km I get at this stage is a bonus :p

Btw I did clean out the PCV valve a while back. Can always order a new one for good measure.
No way 30k oci did this.
That is crazy.....some of the sludge looks like lava rock.
Manual cleaning is s must.

Something is fishy here......did they run it in extreme heat?