too late for synthetic oil?

[KeithD]

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:

[sloopercat]

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.

[zank]

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.

[ITSUKI Drifter]

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

[Henge]

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?

[Supra Bob]

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..

[Malibyte]

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!

[MkIISuperSupra]

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

[CJSREDPRA]

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:

[BACK2SUPRA]

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

[Henge]

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

[Dave A.]

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.

[Dave A.]

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.

[Phoenix]

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:

[supramantt10]

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

[CJSREDPRA]

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

[Funkycheeze]

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)

[supramantt10]

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?)

[supra85]

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.

[Phoenix]

Can anyone weigh in on problems experienced when switching back to dino juice from Mobil 1??

[StanS]

STP brand "Stop Leak" will help with the seal leak problem. I've found
that it's the best working brand other than Justice Brothers which is slightly better but costs about $8-9 a shot.

[Phoenix]

Ok. I did it. I changed back from Mobil 1 to jungle juice. I'll let y'all know what happens.

[Dave A.]

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:


Switching back to conventional oil can have an adverse effect on oil seals that have become conditioned from the use of synthetic. The oil seals can slowly shrink and harden back to the state that they were in before you switched over to synthetic, and that can cause oil leaks. The risk of this happening is generally considerably greater with high mileage engines though and is much less likely to occur on a low mileage engine.

Why are you switching back to conventional oil??

[Dave A.]

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.



Good synthetics have good detergent additives that tend to clean the engine internals with time. This can be a good thing or a bad thing depending on how much crud build-up is inside the engine. Varnish is a common deposit that forms with conventional oils and eventually gets dissolved by synthetic oil additives. Any deposits on the bearing inserts other than a possible slight film of varnish shouldn't be there in the first place. 8)

A non-rebuilt turbo shouldn't suffer any damage as long as the bearings are in good shape and not worn.

I always reccomend synthetic for low mileage engines only, or for engines that have just finished the break-in period (8,000 miles or more). Switching to synthetic on a worn, high mileage engine is always a risk.

[Phoenix]

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:


Switching back to conventional oil can have an adverse effect on oil seals that have become conditioned from the use of synthetic. The oil seals can slowly shrink and harden back to the state that they were in before you switched over to synthetic, and that can cause oil leaks. The risk of this happening is generally considerably greater with high mileage engines though and is much less likely to occur on a low mileage engine.

Why are you switching back to conventional oil??


My engine was holding oil before I put in the Mobil 1. The Mobil 1 caused it to start leaking/burning oil. A bit at first but it was starting to speed up. So I switched back to GTX. If it keep leaking at least it wont be so expensive to top up. There's no way in hell I'm changing my seals again until I rebuild for turbo. I knew I was taking a risk when I put the mobil one in. I let you know what happens with the switch back. 8)

[Donn29]

ah shit, why do i have to read this after changing the oil.... seems like it may be burning some nnoe, but i did put lucas oil shit in 100kms after the oil/filter change.

[Phoenix]

ah shit, why do i have to read this after changing the oil.... seems like it may be burning some nnoe, but i did put lucas oil shit in 100kms after the oil/filter change.

Damn, I'd have warned you if I knew. Who knows, maybe the Lucas stuff will save you. That stuff is good. I put half Lucas/ half sythetic gear oil in my noisey diff a short while ago. At very first it was louder if different at all. After a while it started getting quieter and smoother. Now I hardly ever notice it. I might not need a new diff so soon after all.

I used lucas on my engine back when I had leaks everywhere and an ocean of oil between my cam towers. It upped the performance untill I increased the concentration too much. I wouldn't use more than a quart of that.

[FordRocks21]

Ok here's my situation...

I got an engine swap from Lone Star Engines in Dallas (I wouldn't recommend them) and they put 10W/40 in for the first 500 miles, then they changed the oil and put 10W/40 in again. When it came time to change the oil again, I hadn't driven it much because the lifters started clicking (or thats the best anybody could assume without opening up the engine again). So trying to keep the warranty from voiding, I changed the oil while it sat in my garage with Mobil 1. That oil probably had about 100 miles on it before I drained it and took the pan off to check for crap in it. Turns out that they had used silicone instead of gaskets or on top of gaskets and little pieces of it had fallen into the oil pan which then clogged the mesh on the pump. So currently, the pan, rack, and suspension is off of my car (I went ahead and decided to upgrade/replace everything under there while I was at it) and I'm about to put it all back together and be able (hopefully) to drive my car constantly 9 months after my swap (thanks to Lone Star and their complete lack of customer service). I honestly have no idea what they replaced. For all I know, all the parts could be old except for the major parts (thats my inclination). I'd rather use cheaper oil for the next 1000 miles or so to make sure I've fixed the problem but should I stick with the synthetic since I've already switched? The idea I get from reading the rest of the posts is it shouldn't matter since my engine is fairly new (or supposed to be). Anyway sorry this is so long, I was just wondering cuz this problem of switching to synthetic and back is new to me.
Thanks,
Derek

[Donn29]

if the gaskets are new, then you should be ok.

[Dave A.]

Hmmm.....depending on what type of silicone the "lone star" gang used to seal things, some synthetics can chemically react with certain types of silicone sealants. Mobil 1 may be especially vulnerable to reacting with certain silicones, but I haven't proven this as of yet. I know that a couple of Amsoil gear lube formulas can react with a sealant used by GM on some of their transmissions and driveline components. FIPG should be used on the oil pan when possible to help eliminate this possibility. What did you use to re-seal the oil pan?

Switching back to conventional oil in your case shouldn't have any adverse effects as long as the Mobil 1 hasn't attacked the sealant on the oil pan.

[FordRocks21]

I haven't put the oil pan back on yet. I'll be doing that Tuesday when I'm finally able to be home for any extended period of time. What kind of sealant should I use? The book says to put it on the 4 corners of the gasket.

[CJSREDPRA]

What year is this motor????

82 - 83 motors use a gasket. 84+ (I think, I know 85/86 does) uses FIPG (Form In Place Gasket) as the gasket material, you will need to use most of the tube of this stuff on the sealing areas/surface, not just on 4 corners.

[FordRocks21]

Yeah I just got back from napa and the guy told me to put silicone on the whole thing. It's an 84.

[Dave A.]

Use FIPG instead of silicone. Much better!

[FordRocks21]

What's FIPG and whats the difference?

[Dave A.]

FIPG (Form-In-Place Gasket) is a product used by Toyota for sealing engine oil pans. The exact formulation is unknown, at least to me, but it definitely resembles a silicone based type sealant. Synthetic oil won't react with it like some other silicone based sealants. I highly recommend it if you plan to use synthetic oil. Works great on the diff. cover too! 8)