Should I use synthetic oil ?

My wife had a 2002 Rav 4 AWD, we had it for years and I always used Synthetic in it in hopes to make it last a long time. The manual called for regular old dino but figured I was smarter than the average bear. Anyhow, she had developed valve tick, the cam chain noise and valve seals worn so it would puff some blue smoke when it was cold started at 80,000. Researched the crap out of it and found that if the manufacturer does not call for synthetic, definitely do not use it.

Synthetic is much "thinner" and designed to be slick so it can do a good job at lubricating but can seep through the valve train. The seals in the entire engine aren't designed for synthetic so they won't swell properly either. Even though I religiously changed the oil and maintained the car, I noticed some seepage on the valve cover gasket and sump but thought nothing of it brushing it off as normal wear. She recently had to trade her in since cost to repair the Rav would be a substantial down payment. 146,000 miles on the ODO. Still not bad but I think it had much more to go if I stayed with dino from the start.

A friend of mine has a 2002 Camry (same engine as in the Rav) and has 230,000 miles regular dino and the motor runs very well with only a cam chain adjustment and now a new transmission. No ticks not a drop or leak.

During that time I had an MR-2 Spyder which I didn't care for as much and used regular old oil. Drove it pretty hard and daily. Never had a problem or tick on that engine. Got tired of the small sports car and went with the Taco partially since she lost the Rav. Anyway at 138,000 it still drove like new. As always YMMV just my experience.

 

Just FYI, they break each and every motor in at the factory, to make sure everything is working properly. Thats just a myth.

 

Yup. I bought half synthetic for my wife's ride, and it said something about high mileage on the label. I don't know anything about regular vs synthetic, so I figured just go between.

 

They switched from using 5w-20 to 0w-20 by default from the factory and book on the 2TR-FE engine. I still use 5w-20 in mine since it's cheaper. The reason it is synthetic is you cannot buy 0W-20 regular; it's only available as a synthetic.

 

my 2.7L '95 tacoma has almost 400k miles on it before I sold it. I did its first head gasket at about 350k. I used whatever I can find cheap (non-synthetic oil like penzoil, castrol, quaker, etc...) in the store.

Now I just picked up an 2005 2.7L 4cyl with about 89k on it. Engine sound smooth and it's time for oil change. The previous owner runs reg oil in it. I'm thinking to stick with reg oil but I also heard lot of good things about that M1 oil.

I also have 93 Mazda RX7 (rotary motor of course) and a miata - both have never see synthetic and no problem with their engines

I want to give synthetic a chance but seen too many pros & cons. Probably safer to stick with reg oil? What you guys think?

 

I switched over my 2012 V6 Taco to synthetic at 3K miles and the only advice I got from the dealer was that I would experience problems if I were to switch back and forth at a later date. What I took from this was that once you have significant mileage, it is a bad idea to change either way. I made the choice because many of today's engine are prone to sludge buildup when using regular oil.
My '09 Avalon developed a slight tick during warm up that I noticed at some point after changing to syn oil at 5K miles but the dealer claims that it was normal for that engine and as of at 60K miles there have been no other issues. For my Taco, no ticks and no changes in performance as of 12K miles.