What Causes High Oil Use On 1.8Vvti

[fastbob72]

Now there is a question that everyone believes they know the answer to, every pub expert and would be mechanic will confidentially proclaim they're opinion as fact dependant on what they've read or been told but either way the general consensus based on the now urban myth of the vvti's oil problems seems to be it's a badly designed engine that's inherently fragile and best avoided at all costs.

The truth is as the truth of anything always is not as simple or as black and white as it is often believed.

That the vvti has a potential oil problem is beyond doubt and if you search the internet you'd be forgiven for wanting to avoid them like the plague.I bought my vvti 3 years ago assuming it was 7A-FE based engine with some form of VTEC style system added to it.My experience of Toyota was limited at that point. Ask me anything pertaining to Ford or Vauxhall in particular and I could tell you anything you needed to know but Toyota, I had much yet to learn including how the vvti system worked and that itnwas a whole new design of engine.Of course by the time I'd bought it it was too late to take oil problems into consideration the money was spent and I owned the car but I've spent the last 3 years researching and wondering when my car would develop the almost inevitable oil problems that ALL 1zz-fe engines are destined to suffer with.

What I've found out though is that far from being a foregone conclusion or that it's a weak flawed engine it is a real peach of an engine that is robust and capable of high mileage and heavy use if it's been looked after properly and you continue to keep on top of maintaining and servicing it as it's meant to be.Some prior knowledge of it's potential issues will also help in keeping on top of the problem. Unfortunately in your case it's too late but if you intend buying a reconditioned engine then find out for definite whether it's been fitted with the later pistons, rings and oil capacity that Toyota deemed necessary when replacing customers short blocks under warranty when they developed oil burning problems.

Let me explain.In order to make a lighter, more powerful yet economic engine to replace the 7A-FE Toyota engineers used several stategies in order to accomplish it. One stategy was to use lighter materials i.e aluminium block and hard plastic inlet manifold while another was to reduce friction and pumping losses in the engine by using low tension piston rings which in theory is a good idea but in practice it appears that they didn't always seal well enough resulting in blow by gasses escaping past the rings allowing for oil to be burnt. Added to that they only had 4 oil drain back hole in the ring glands under the oil control rings that were also unnecesarrily small that could easily get blocked up if the oil wasn't clean ir full of particulates. This encouraged oil glazing to build up on the pistons and inhibited the oils ability to cool them creating a self perpetuating problem i.e. hotter pistons means more oil deposits building up and more build up and glazing impeded and restricted the flow of oil making the engine run hotter (though of course you wouldn't see any difference on your coolant gauge as it measures temp of the coolant after it exits the engine).

of course this problem would be bad enough but in a spectacular own goal by Toyota they gave the 1zz, by anyone standards a small oil capacity, of 3.7 litres inc oil filter when you consider that the average engine of similar size had 4.5 litres or more.

What this means is that literally as soon as the oil drains back to the sump it's drawn straight back into the engine to work again whereas with a larger volume of oil would mean there is always a pool of oil in the sump allowed to cool, even if only a little, before being drawn back into the engine.This cannot be an ideal situation for any engine but remember the 1ZZ-FE engine is using oil pressure to work the vvti system aswell as it's usual duties that all engines require of their lubrication systems.

Now, if the car has had it's oil changed at the regular intervals recommended by Toyota,has used the correct grade of oil AND hasn't bad the nuts revved off it day in day out then there is a really good chance it won't develop any oil problems at all. I bought mine with 78,000 miles on the clock with 2 previous elderly owners and a full service history at all the required intervals so it was no surprise to find out, a relief aswell, that it used very little oil and way above the minimum miles per litre of oil that Toyota say is ok, that is the after they revised it in light of the engines oil problems.

This is of no solace to somebody who has bought one that they later find it has a problem with oil useage....... and exactly how can you tell on a test drive if somebody deliberately tries to hide it. I mean I checked the oil straight away on checking my car out, looking for the oil level and condition and then after a thorough test drive and letting it settle and cool for 10-15 mins checked it again but if somebody had changed the oil before selling the car and like me you didn't know there was an issue with those engines how could you possibly tell there was a problem just by checking the dipstick and a test drive.

I cannot remember off hand what the minimum level of oil consumtion is on these engines, something like 1000-1200 miles per litre i think but don't quote me on that but on my own terms it was what I have always considered too high am oil consumption...... i learned very early on the hard way how important oil is to any engine so it's something I've always been incredibly aware of so you can bet I've kept a very obsessive eye on the oil level of my motor and changed it with filter at the most ever 3,500 miles now. To begin with there never seemed to be much useage, about 2400 miles to a litre which if it had been a Vauxhall engine would have beem enough to raise an eyebrow but by Toyotas reckoning was well above the recommended minimum oil consumption level but it also meant I was reluctant to really rev the engine or use it hard like I normally would a car that responds to that sort of treatment and the vvti does respond to being revved much more than the 1.8 it replaced.

It was off the road for more than 9 months until march this year and i drove nothing but diesels in that time so when I got back on the road in a petrol engined car I found myself much more inclined to use the engine much more freely, not only that I found it much, much more satisfying to drive if I revved it harder than I had previously. The trouble with that though is that the oil useage is greater the harder the engine is used. This last month because of the icy roads,the amount of water lying in the road or the snow I've been driving more carefully and at lower speed and revs and barely used any oil at all whereas during the summer over the same period I may have used a litre in the same time.

Obviously the first thing that springs to mind in light of all the sheer volume of content on line about them burning oil is that it's being burned, it's almost a self-fulfilling prophecy lol but I've never been one to take the opinions of others over going and checking things out for myself whether that concerns oil consumption or absolutely anything else at all so I went about checking and testing everything I could to determine where my oil was going. I pulled out the plugs, checked the. state of the exhaust tail pipe for signs of excessive soot, did a compression test etc, etc and could find no signs of oil being burnt that I would expect to find yet there were never any signs of leaking either. Never oil stains under it overnight or fresh oil stains anywhere on the engine or where there where some it never increased.

It wasn't until I had to fit a new radiator and found it easier to access some parts through the wheelwell after removing all the plastic liners that I noticed some fresh oil around the powersteering pulley and from around the timing cover towards the back of the engine. One consequence of renewing the oil regularly with fully synthetic is that it's quite thin and rarely turns that thick black that most of us picture of used engine oil plus the fact it's incredibly difficult to see what's going on looking from above down the side of the engine bay it's very easy to miss the signs of leaking oil from that area plus in my case at least the leak doesn't appear to be bad enough to leave pools of oil behind,it's parked overnight on a gravel drive so it would be hard to spot unless it was thick, black puddles anyway, thin light brown oil that leaked overnight would be more difficult to see besides once the engine is switched off the oil will stop leaking anyway so unless it's excessive and there is a lot of it on the side of the block then there will be little sign of it when it's left overnight.

Personally, I suspect that a reasonable amount of cases where obvious signs of oil leakage aren't immediately found then it's been put down to the infamous oil burning problem and dealt with accordingly as more and more this problem is found then that's what owners AND Toyota technicians are expecting to see and unsurprisingly that is what they find.

All in all none of this is of any consolation if your engine has already blown but I hope it goes someway to explaining the problems and perceived problems of this particular engine.

Bob

Sent from my SM-N910F using Tapatalk

[paulsos]

I wondered what was happening with my 2001 avensis petrol, uses a massive amount of oil but no apparent leaks, no blue smoke... can/would changing the oil sump to a higher capacity one (if possible) ease this problem? I bought my car last year with only 86000 miles on the clock and although the dealer could only provide a couple of MOT's, didn't think that there would be any problems. Found out to my dismay that it gets through so much oil that i have to check it each week. 

[MrD0ta]

On 11/23/2012 at 8:31 PM, Devon Aygo said:

PM your chassis number to me and I will check

Hello!! Would you also be kind enough to help me with this also? I have an Avensis 1.8 2005.

[Konrad C]

Considering the subject of 1.8 VVT-i 1ZZ-FE engine oil consumption has been heavily covered on this forum, plus the fix happened back in 2005, there are few options you have now. You could keep topping up the oil, unless it's so excessive and also affects the emissions and contaminates the catalytic converter. That's the cheapest option.
The other option is to find a revised engine from a later car, which has been scrapped for other reasons. But you will need to balance the cost and overall condition of the car! It might be better to buy another car.
Personally I would take stock of finances, the condition of the car, cost of repair, then make a decision if it's worth it.