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My 84 has almost 195,000 miles on it. Me and the previous 2 owners have only used regular oil for the engine. At this point in time, is there any significant advantage to switching to a synthetic oil? I'm using synthetic oil in my new wheels from the get-go; I plan on keeping it forever.
But for the Supra, is there a benefit to switching, or not?
Thanks,
KeithD
:morning:
 

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Don't see a benefit. There are some folks, me included that think you will have a tendency to leak oil after the switch. It happened to me on a 80K mile Camry. I am sure you will hear other opinions as well. If Dino was good for 195K, what's wrong with that picture?

And yes, I will use synthetic in my newer vehicle.
 

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the first 5M i rebuilt i used non synthetic motor oil and it never leaked, but after breaking the engine in i switched to synthetic and it started leaking like hell. I'll never used synthetic on an old engine again.

Thats my experience with synthetic oil, others might beg to differ.
 

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synthetic oil

I use MOBIL 1 synthetic on my built 6M... I used a regular Valvoline 10w-40 to break in the motor for about 500 miles daily driving then switched to Mobil 1 15w-50 synthetic oil and it never leaked....

It is only to how old your car is... with nearly 200K miles on the motor... it is a possibilty that it will leak for the old regular oil helps the gasket seal up while as soon as you change to synthetic on a 200K motor... the tendency is to leak for the synthetic oil is thinner than regular oil and the particles are different
 

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I put senthetic on my motor that has 170k and it leaks like hell...can I switch back to regular and not get a leak anymore?
 

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Nope... once you go synthetic, you can never go back unless ya change out all your seals... which is why I haven't gone synthetic on mine yet. Not until I drop the new motor in anyway..
 

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I've been running synthetic in my '84 since it had about 120K mi on it (now has about 218). No leaks...anywhere...never did (except when the PS pump began to go last year - fixed right away).

The '85 has about 77K on it....don't know what the previous owner used, but I'm told he took very good care of the car. It had its first oil change in my garage a few weeks ago...synthetic, of course. No leaks so far!
 

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I've switched 3 engines to Amsoil and have no regrets at all. Not a drop leaking out of any of them.

5mge with 100K miles
5mge with 170K miles
7mgte with who knows how many miles...

Neither of the 5mge engines had been all that well cared for but I may have been lucky. I would never consider switching back.

Amsoil gear lube in the tranny and rear ends of both 83's as well.

one and two years later, I still can't believe the difference Amsoil made in how quiet the engines, trannies and rear ends now run.

Leslie
 

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KeithD,

In regards to the previous 2 owners, how good were they on "regular" oil changes???? In other words, how often where they changing them???? 3K miles, 4K miles, 10K miles, Once a year (regardless of miles). It's good to know that at least they were changing the oil & using petroleum, but how frequently was it being done???? This is one of the key's also.

In my case..... I've had my Redpra for 12 1/2 years (since it had 75K miles on it) and since then, I've put on another 202K miles on it. Back when I bought it, synthetic was still pretty expensive (like everyone was still selling it for ~$9.00 a quart). For me at the time, it was still a bit on the expensive side, so I figured I "should" be fine if I stay w/ petroleum & change the oil every 4K miles. And that's what Ive done for the last 12 1/2 years. My front end seals have been changed out 2x, the cam cover seals have been changed at least 2x - 3x, the rear cam seals have been changed 1x, the cam tower seals just got changed for the first time, and my rear motor seal has not been changed out yet. At 277K miles, I'm still in no hurry to switch to a synthetic, but for the last 25K miles, I've "sort of" been using a synthetic (it's been that High Mileage stuff & I have not had any problems). I'll probably go to a full synthetic when this motor gets a full rebuild. At this point, I'm also figuring that it might be too late to switch to a full synthetic right now w/ the motor in it's present condition, despite the regular 4K miles oil changes.

In the case of the Silver Slug, it only had 48K miles on it when I bought it, & it currently has 51K miles & is due for it's next oil change. When I did the first oil change, I went w/ the cheapy Toyota 10W30 petroleum that Toyota sells @ the dealer. Just mainly to see if the motor has any leaks (no leaks at all). When I do the next change, I'll be using the Castrol (can't remember the exact name) synthetic "blend" which is the the part synthetic/part petroleum mix (still 10W30). If the motor is still not leaking, then I'll go to a full synthetic on the following oil change. This way, I'm doing a gradual switchover, in case there are some problems that pop up. Plus now, synthetic is much more inexpensive (Mobil 1 is around $5 - $6 a quart), so at least now I can afford synthetic. :painting:
 

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Mobile 1

Just replaced my regular dyno with Mobile 1 15W30. However, I used a product called AutoRX before I made the switch. Check out Bobistheoilguy.com. Lots of techie stuff on the forum. It lead me to AutoRX, which is a type of engine sludge cleaner. It also acts to help seal gaskets.
Its only been several 100 miles but no leaks so far. Engine is much smoother and quiet. BTW, I have 93K on the original engine.
Good luck
Al
 

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What would happen if you did go back to regular oil from synthetic?
 

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Some synthetic oils have an inherent tendency to disolve crud and carbon build-up inside a high mileage engine, which in some cases is about the only thing keeping the old gaskets and seals from leaking. :? The original gaskets and seals on high mileage engines deteriorate and become hard, brittle, and crack. Some synthetic oils contain an ingredient that will actually soften or partially rejuvenate the seal material which is okay as long as the seals are free of cracks. OE Japanese manufactured gaskets and seals last considerably longer than American made gaskets and seals so they are, lets say, more forgiving in a lot of cases. But, in my honest opinion, it's best to use synthetic on a low mileage engine that has tighter clearances, minor internal crud, and good resilient gaskets and seals. To answer your question, switching back to a petroleum based oil is risky but is less likely to cause a problem on a low mileage engine.
 

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Chris, and anyone else who may be interested in a good and less expensive synthetic lube, check out the Amsoil XL-7500 series synthetics. Less expensive than the regular Amsoil synthetics but with many of the same good qualities. You can read about it at the Amsoil web site, www.amsoil.com. I can probably get the XL-7500 lubes for about $4.50 per quart or about $16.50 per gallon with my dealer pricing.
 

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Dave A. said:
To answer your question, switching back to a petroleum based oil is risky but is less likely to cause a problem on a low mileage engine.
Why is it risky Dave? I was thinking of doing that tomorrow. BTW I don't think anyone mentioned it. I takes quite a while for this process to occur so don't think you're out of the woods just cuz everything is great after the switch. :wink:
 

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I was thinking of switching to Royal Purple synthetic in the future. The engine has about 16,000 miles on the rebuild so I won't worry about leaks. Should I flush out the engine first . . . is there a specific substance I'm supossed to use before I put the synthetic oil in? Or should I use a blend and then the next oil change use full synthetic . . . or does it even matter?

-Keith
 

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Personally I would not go anywhere near Royal Purple. Do a search on said subject & see what I last posted about this.
 

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my maxims regarding synthetics are as follows:

1. mobil invented the stuff with mobil 1, so i stick with that - its cheap at wal mart. redline makes good transmission fluid and lightweight gear lube

2. because if its gunk cleaning properties and different molecular structure, it can make a high mile engine with small, often undetectable leaks much leakier

3. synthetic lube can make a noisy diff noisier

4. redline fluid works great on boxes that use cone synchros (most, including W58 and R154) but stick to the special factory fluid to any box that uses plate synchros (V160 and other getrag, high end tremec such as T56)

5. DO NOT use synthetic in a dogbox - you lose about 90% of the shifting feel and thus grind the hell out of the dogs (and make the driver angry)
 

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CJSREDPRA said:
Fluids: Not quite as familiar w/ Royal Purple tranny or rear diff fluids. Have heard LOTS of bad things about their engine oil, I'd say stay away from them. I believe it was Phil Dupler who had problems w/ them on his 6MGTE, he was getting much LOWER than normal oil pressure readings from them. Dumped it out & put something else in & oil pressure went back up to normal.

Here's a nice scary story from 6 years ago. One of the very first guys to be running 600+ hp on a street driven MKIV down in Texas, was Bryce Danna. Tried Royal Purple for the first time from a recommendation from someone. 500 miles later, he decided to change the oil to see how it looked. When it came time to drain the oil from the pan, the oil just basically POURED out like WATER!!!! The oil had lost all of it's viscosity. RP's motor oil does not come hightly recommended in the Supra community (this was from a thread I read 5 - 6 years from the newsgroup on www.MKIV.com).
Yipes . . . :shock: Maybe I'll go with Mobil 1. :shifty: Thanks for the info Chris!

-Keith

(Anyone know about flushing the engine 1st?)
 

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I have heard that switching to synthetic on a high milage engine is not a good idea because the oil scrubs out deposits on the bearings and could actually cause the engine to start knocking.

My question is what effect would this have on a non rebuilt turbo? My 7mgte should be done soon (I hope) and I have been thinking about running synthetic after the breakin. I have had work done on the head and worry about the thinner oil blowing by the turbo and ending up in the head/combustion chambers. Any help would be great.

Thanks.
 
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