Celica Forums General Discussion General Is it safe to switch to synthetic?

TL/DR what are the risks with switching to synthetic? I am afraid of dislodging deposits or sludge or something.

My wife's 02' GT with 122k miles has been burning a quart every thousand miles since about 80-90k.

She drives quite gingerly, never gets near redline.

She's ran it down 2 quarts low at least 3 times and driven 50 miles home at 70mph like that, had the oil light come on once 10 miles from home too.

I believe it's the crappily designed oil rings in her engine that are at fault. I changed the PCV valve already as it was due. I had heard synthetic oil can help as while in engines with worn out piston rings it worsens burning due to smaller molecules in synthetic oil, the smaller molecules pass through the gummed up, undersized oil ring holes easier.

My concern is she may have deposits from those times she ran so dang low on oil it started making a diesel rattle sound.

She still routinely ends up a quart, sometimes a quart and a half low (she likes to be responsible for her car...). The oil gets pretty black compared to my Corolla with the same engine and more miles.

I am afraid of them getting dislodged and causing problems if I go synthetic. That's what I am told can happen at least. Should I be concerned about sludge, and about synthetic causing complications?

It is just fine to switch to full synthetic high mileage on your Celica.

This is what I've been using on my 2001 Celica since about 2002, through now, 2021.

CelicaHobby affiliate link: https://amzn.to/3hQ4eI6



You can usually find it for about $25 and up

edit, also skim through this -
https://blog.amsoil.com/is-an-engine-flush-good-or-bad/
research "engine oil flush"

Tman,

The oil return holes on pistons may be clogged up with carbon deposits.

Try first to clean them out with Motor Medic GUNK $4 in Walmart. It may open up those holes and let oil return to the crank case instead of the burn chamber. It should also clean any carbon deposit on piston heads and valves that cause dieseling.

I had a bad case of low compression on Cyl1 due to running a 2ZZ engine at high speed on long trips with 87 octane, never changed, only added oil and other abuses Engine was shaking badly on idle and low RPMs. No oil or fuel additives helped. A few reputable shops gave up, recommending $4K engine swap.

I flushed the engine with the GUNK, using only half strength, idling engine 15 minutes. Dumped oil was black and sludgy. After 2nd flush, compression came back even. Engine was smooth and strong again after 320K miles. I do abuse and run that car at high speed a lot. From then on I always flush engine with GUNK at half strength every oil change. Valve head looks pristine clean, no sludge, no deposit. I alternated regular and synthetic oils, no problems.

Better yet, if you can find a 7th gen GTS in decent shape, buy it for your wife. That engine is strong, car nimble to drive. Your wife will love it. I was considering buying a hydrogen fuel cell Mirai with all the new incentives, but I don't want to give up the fun of driving the GTS and float around in a boat hehe.
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I use Mobile1 in mine and have been since about 150k