The biggest issue with the 00-02 engines were the oil drains in the pistons. They would get clogged up and cause the car to burn oil and eventually kill the motor.

 

The MR2 is just as bad. Stick to facelift models or one with a great service history. Otherwise be prepared to do an engine replacement or swap.

 

The Consumer Reports article documents the well-known engine sludge problem that affects 1MZ-FE (3.0 v6) and 5s-fe (2.2 4cyl). Over the years I have opened many of these engines to find what looks like the aftermath of a forest fire - heavy black carbon deposits clogging up every gap and every passage. I have replaced many of these engines due to this problem - in fact I am working on replacing another one right now.

The sludge issue never affected the 1zz-fe. Whoever said that was seriously misinformed. I have never seen a sludged up 1zz. 1zz-fe does not have a tendency to sludge. It has other problems, that you can read about in great detail on this forum. Tbe main issue is excessive oil consumption, due to defect in piston design. This same issue affects the 2az-fe 2.4-liter 4cyl. I just got through replacing one of those.

Toyota reliability, brah.

 

The Consumer Reports article documents the well-known engine sludge problem that affects 1MZ-FE (3.0 v6) and 5s-fe (2.2 4cyl). Over the years I have opened many of these engines to find what looks like the aftermath of a forest fire - heavy black carbon deposits clogging up every gap and every passage. I have replaced many of these engines due to this problem - in fact I am working on replacing another one right now.

The sludge issue never affected the 1zz-fe. Whoever said that was seriously misinformed. I have never seen a sludged up 1zz. 1zz-fe does not have a tendency to sludge. It has other problems, that you can read about in great detail on this forum. Tbe main issue is excessive oil consumption, due to defect in piston design. This same issue affects the 2az-fe 2.4-liter 4cyl. I just got through replacing one of those.

Toyota reliability, brah.

Oil sludging issues are primarily related to how well the Positive Crankcase Ventilation system works. The big issue with some older Toyota (and other) engines was that many of them (like the 4age) actually had no PCV systema at all, just a vent from the valve cover to the air cleaner. This allowed the blowby gasses to escape without building up excessive crankcase pressure and preventing raw blowby gasses from polluting the air (blowby has a lot of Hydrocarbons along with NOx and water vapor), but did not actually ventilate the crankcase. A real PCV system continually pulls in fresh air (through the PCV valve) to clear out the blowby gasses. Blowby gasses (especially the NOx) help degrade the oil in the crankcase, and the ventilation helps clear out the water vapor which causes sludging. Really well-designed PCV systems is one of the reasons why 7000-mile + oil change intervals are not so bad for modern engines. There are also some older engines that had PCV systems and still were very sludge-prone because the the fresh-air circulation path inside the engine did not flow through the lower regions of the engine.

Dave

 

Yes, oil consumption is documented - "The main problem is the design of the pistons and piston rings. Toyota used a piston that’s too small and compensated by using larger rings. Over time, the piston rings wear down and begin allowing excess oil to pass by the rings. If the rings wear down too much then cylinders start losing compression, which is a big issue. It’s simply important to keep an eye on oil levels. The 1.8L engine has a pretty small oil capacity and running it too low on oil can begin to cause extra wear."

 

I have had two 1zz's apart. The problem I found was the oil control rings where frozen in the piston land. The compression rings where fine. I had a 98 Corolla with a 1zz that started using oil at 50k. It had oil changes at 3k intervals. I am pretty sure I did not use synthetic oil at that time.

 

Toyota introduced the revised 1zz piston-ring design for USDM in 2003. For EUDM it was not until 2005. These different dates for the introduction of the fix causes confusion because people are not aware of the difference between markets. Regardless, the issue initially affected all 1zz of all origin in all vehicles. Early on, Toyota had a engine replacement program for affected vehicles. Some of the old-timers on this board (almost all gone now) did get a free engine from Toyota out of the deal.

 

Toyota introduced the revised 1zz piston-ring design for USDM in 2003. For EUDM it was not until 2005.

In effect meaning that we never got the updated piston design in the MR2, meaning that motoring press and internet comments on earlier vs later MR2s were and are bs for us.

Concerning the multi grade oils, the info on the polymers breaking down is not really relevant anymore for even hárd road use under high temp conditions. It still is road use, not racing and the modern synthetics are well up to it.

Which leaves the last confusion; the oil level/quantity. There are comments on the later engines having more oil and also about that being simply a different dip stick ´asking´ for half a litre more.
Not found the ´definitive´ on that. Sticking to the level indicated on the original dip stick in mine.

 

I've taken apart my fair share of 1ZZ motors (even ones that lived through a lot of shit) and have never seen a single one with sludge problems. What they mean is oil consumption due to the piston design, OP.

Happens when one goes on long intervals for oil change with non-synthetic fluids or something of low quality. After some time, the return holes on the piston will clog up with sediments from dirty oil and eventually sieze your rings. Oil has nowhere left to go after that and burns off in the combustion chamber. The pre-2003 pistons have only two return holes on each side that are VERY small. For 2003 model years or production dates from late 2002, Toyota doubled the number of holes and also enlarged them.

I've seen older engines with the "bad" pistons burn little-to-no oil, but those people also maintained their cars.

It all comes down to maintenance. Even the revised pistons will clog over a long time of neglect. Just will take longer

 

Happens when one goes on long intervals for oil change with non-synthetic fluids or something of low quality. It all comes down to maintenance. Even the revised pistons will clog over a long time of neglect. Just will take longer

Since most MR2s now have 100-200k miles (mine are 90,120 and 150k) and synthetic companies market HIgh Mileage oils, I've started using these oils and step up to slightly thicker viscosity as well to get a better seal. Your thoughts?

High Mileage Oil: A Practical Guide

Do you need high mileage oil for you vehicle? Read about when to switch to high mileage oil, differences between high mileage oils and more.

www.machinerylubrication.com

 

I've ben used differents oil grades (2003 engine - statement between 145.400~186.411 miles)
Driving style : legal street use, straight line/corner/roundabount acceleration.

• Motul 15W50 300V for testing - way too thich (drove 40 miles)
• Motul 8100 10W40 - oil consumption of 0.70cl per 1550 miles
• Motul 300V 10W60 - oil consumption of 0.70cl per 1550 miles
• Motul Sport 5W50 - oil consumption of 0.75cl per 1121 miles

Motul 10W40 is the limits for the 1ZZ-FE for a good oil lubrification without feel any engine difference.
Motul 300V 10W60 is a little bit too thich (drove 3106 miles). I felt the engine requiring more effort on middle/high rpm.
I stay with Motul Sport 5W50 while keeping eyes on oil dipstick every 1121 miles before attempting driving hard on corners.

 

This website about oil updated Aug 14, 2022.

MOTOR OIL ENGINEERING TEST DATA

….On smart phones, “Q&A” CAN NOW BE ACCESSED BY CLICKING ON THE 3 HORIZONTAL BARS IN THE UPPER LEFT HAND CORNER…..******..With so many different Blog readers coming here…

540ratblog.wordpress.com

 

You can still use a 40 weight oil in a colder climate but you need to use 5W40. It's what my Cayman uses - a little more expensive and harder to find than a 5W30. I was once told the wider the spread is between the cold and hot viscosity the more susceptible the additive package is to breakdown from very high temps, not sure how much value there is in that statement but it's food for thought.

 

Thank you super Dave Osborne will change my PCV [emoji869]

 

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