[uneasyrider]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Formula8:
1. I've owned several Toyota's and not to change the subject and no offense but your story is routine for a Toyota. Good story but IMHO, it does not serve as proof of anything other than Toyota builds good cars and trucks.

2. What is proof to me is the extent sythetic oils are used in all forms of racing and recommended by virtually all high end auto manufacturers for their street cars. Many of which have been able to eliminate external oil coolers as a result. Yes, synthetic costs more and in many typical cars, you may never know the difference. But, I guess the same thing could be said about forged cranks, forged pistons, Crower rods and so on. Depends on the application and the owner's willingness to take on risk. </div></BLOCKQUOTE>

1. Yes they do, and I am a mechanical engineer and I used to be a diesel mechanic and my best freind is a Toyota certified mechanic and I can tell you that the BEST made rig wont last very long if the oil is junk. I don't care what it's made of and how well it's put together if the metal contacts metal it screws it up.

2. I think you said it "...Depends on the application..." Willingness to risk hasn't got a thing to do with it. The manufacturer sets up a maintenance program for that engine/application and a service factor for said and if you follow the manufacturers guidelines you should be just fine. The auto makers do a ton of testing to keep there customers happy and keep from paying out warranty claims. It isn't ALWAYS perfect of course but I can guarantee they don't put anything in the engine that wont make it last. Now if synthetic is recommended you better use it, that goes back to the manufacturers service factors for that application. I'm not saying that synthetic isn't good but I don't think it's necessary for most applications. It might be a budget saver if the oil change interval is such that it cost less to change synthetic less often.

[DAVE RIBEIRO]

Syn Oil is used by most race teams and it does run cooler,lower engine temps,less friction,lasts longer,gets better gas mileage(1-2 mpg),keeps engine cleaner...Yes, but it does cost more,so does good Medical insurance,car,etc
There are some many positives,that I can't
see why anyone would argue..But,thats what makes
the world go round..Syn,works if you care about your investment!! if you don't,use regular
oil and good-luck..Life is about Choices...
Dave...1033/stock

[engineer]

POCI and GTOAA national conferences had Mobil One as guest speakers and they confirm not to use Mobil One in a used engine having many miles because it loosens deposits and can cause the filter to plug, it leaks more with used seals that were sealing with conventional oil, and because oil needs to be changed based on either mileage or just age, it is not cost effective for low mileage driven vehicles.

[DAVE RIBEIRO]

engineer,

Where would you put a dragcar,not-driven much
low-miles,lose engine specs..oil changes should still be done at 3-4,000 miles with new filter..How much mileage is a-lot??? 40-50,000.
I don't think anyone was talking about using Syn
in a 100,000 oil burner.. A side from all the little knit-picking things,it still give better mileage,helps on cold starts,etc..just my $.02
have a wonderful Day.. Dave..1033/st

[Toy4Chris]

Glad to see this post got so much action. It seems like the winner is synthetic, period.
Since its not suggested in high mileage vehicles, (+100,000) miles, does anyone know if the so called hi mileage oil is all thats its hyped up to be?
Also, Lucas makes a additive for oil as well, I think it's synthetic, and news on that product?
Thanks
Chris

[Formula8]

Uneaasy,

I think we are all in agreement that we are not talking about a poor performing oil in either case. We are talking about the best oil for a particular application.

My mid seventies 455 barely weezed out 200hp and probably would struggle to make it past 4500 RPM. Now, current technology allows us to ask these engines to produce 450hp @ nearly 6000 RPM on pump gas. Under these conditions, the manufacturers original recommendation mean little. If one choses to adhere to them, I would say, one is taking on a certain amount of risk.

No bad feelings over here, that is why there are dozens of different types of oil. It was said best earlier.....life is about choices.

[Z Code 400]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Darrell:
If that is the case why do tests on the Dyno give more HP with synthetic then dino oil? </div></BLOCKQUOTE>

Lower viscosity = less fluid friction...Robert

[mikeb]

You can switch to synth on a high mileage vehicle.

I swapped the wife's 2000 expedition over to mobil1 at 80,000 miles. No issues, no leaks, no problems. Just less oil changes.

I have read some threads from other people who have done the same with no excitement.

On a much older car with a lot of miles i'd probably just keep running what's been put into it until rebuild time due to the sludge and seal hardening issues.

[jamesgennock]

My friend was a taxi driver and swears by that report.But listen for a second.
Synthetic oil is a chemically specific formula that is perfect every time. Which means that you get the same can of oil each time, with the same protection each time. You add four grams of this and 2 grams of .....
regular oil is refined. You start out with Crude that must be tested to determine its chemical properties as I am sure not all crude is the same to determine how much refining etc Which makes it subject to variations in structure. Alittle help Chemical engineers or mooon shiners. Which doesn't mean it is a poor product but rather something that is refined until it falls between a range of set factors. WHere as the synthetic is perfect every time and isn't on the low end of zinc or moly or whatever oil characteristic sometimes.
My oil background is alittle rusty but hands down synthetic is the way to go. But if you change your oil every 3k or 3 months and are not abusive a good regular oil will be fine I guess.
Couple more things. In every car that I switched from regular oil to synthetic there has beena noticeable diference in performance. They felt smoother and had more power. Believe it or not my wifes 2001 4 cylinder cavalier was night and day different after the switch.
I wish I could have taken pics of my friends regular oil 4.3 versus my synthetic 4.3 engine inside when we did intake manifold gaskets. His was full of scally sooty deposits all over the lifter valley. Actually looked like someone poured burnt wood pieces inside his engine. But no lie my synthetic oil engine was clean and did not have any deposits. And he is a meacahnic that changes his oil regularly. ANyway thats my two cents.

[pippintook]

Many would agree that Pontiacs engines can have rear main seals that leak. 4 spd cars can have rear main seals that are a bit more prone to leakage than automatic cars. There are varying degrees of leaky rear main seals. The experts say that synthetic oil can cause some seals to leak more that may have sealed with conventional oil.
.
I have a rebuilt 400 with about 1000 miles on the engine. Engine is in 78 TA 4spd. The engine was assembled with .002-.003 clearances on the main and rod bearings. Initially, I ran 10w-30 conventional oil. I was noticing that the rear of the engine (by the rear main seal) was leaking a very slight amount. I would get the occasional few drops of oil on the ground after parking overnight. I could see there was a bit of oil in the 4spd bellhousing. I could see that the back of the block by the rear main seal was a bit damp and oil stained. I am pretty sure the oil pan gasket / oil pan seal is good. So, I suspected my rear main seal was leaking a slight amount.The 400 has a BOP rear main seal and I followed the instructions. I changed over to 10w-40 conventional oil (from 10w-30)and this seemed to improve the leakage from the rear main seal/rear of block. I was getting less oil dripage and the back of the block was not as damp.
.
I really like all the benefits of synthetic oil, but I am not sure about how it would work in a Pontiac rear main seal that is a bit leaky.
.
Questions
-----------
1. What are people's experience with synthetic oil and rear main seals in Pontiac engines?
2. Would it be recommended to use synthetic oil in a Pontiac engine ,with a 4spd, that has rear main seal that may have a very slight (ie. occasional drop or few drops of oil from rear main seal if parked over night)?
3. I see different viscosities used for synthetic oil (looks like most run 10w-30 to 15w-40). What do experts recommend for synthetic oil viscosity in normal (ie. engine assembled with .002-.003 main/rod clearances)Pontiac engine?

[uneasyrider]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Formula8:
Uneaasy,

1. I think we are all in agreement...

2. My mid seventies 455 barely weezed out 200hp and probably would struggle to make it past 4500 RPM. Now, current technology allows us to ask these engines to produce 450hp @ nearly 6000 RPM on pump gas. Under these conditions, the manufacturers original recommendation mean little. If one choses to adhere to them, I would say, one is taking on a certain amount of risk.

3. No bad feelings over here, that is why there are dozens of different types of oil. It was said best earlier.....life is about choices. </div></BLOCKQUOTE>

1. Ok

2. My comment was about a stock vehicle, my 1993 Toyota. Current tech? You modified a stock engine, it wouldn't matter if it was 1915 tech or current tech the original design parameters have changed THUS the demends on the oil have changed from stock THUS the manufacturers recommendations are no longer valid so as I stated new service factors then would need to be determined and if synthetic oils or an addative fits those then use it. I was talking about general use. Most vehicles if maintained as per manufacturers specs don't need special oil. Now if the manufacturer recommeneds the oil for your application it isn't really "special" than is it?

3. I don't have any "bad" feelings I'm just trying to make the point that your comment about my Toyota not being a good example (I guess) because they make a "good" vehical is way out in left field. I maintain the vehical per the manufacturers recommendations. I've used the standard type of oil for my application and it has delivered the expected performance. Thus I see no need to spend extra money for more expensive oil. If the manufacturers recommened higher grade oil for my application/conditions I would use it. If the conditions warrent use the oil needed but why spend more if you don't need to. I plan on running Royal Purple in my 462cid E-head engine after it is broken in because it will see the kind of duty that I think demands that kind of oil. If it wasn't going to I don't think I would see the need to spend the money on that kind of oil. The point of me stating the mileage I have gotten out of my Toyota with "stock" oils is that I've gotten the kind of miles on this vehicle that most people would think you would have had to done something "special" with it to get it that far and have it still be in as good a condition as it is but all I did was follow the manufactures guidlines. The engine burns about a half a quart of oil for every 4,000miles and that is still well within the expected oil usage of a NEW engine. It is possible that I might get or have gotten more service life out of the engine if I had run synthetic oil in it but at what cost to benefit ratio? I guess if you had some new car with an engine that was made with poor quality materials you MIGHT want to run a better than suggested oil in it but if the metal is of poor quality the oil quality isn't going to be the key factor in the life of the engine.

[Toy4Chris]

So then is the concensus here that you should NOT use sythetic oil on a motor with over 100K miles on it? Assuming that the oil was changed every 3K miles religiously? Is there any benefit to changing to synthetic that late in the game? I have to say that a 1-2 increase in MPG would be great in a vehicle that gets 12 max.

[carbking]

We put Mobil 1 in a vehicle with over 400k miles. But the way we got the vehicle to 400k miles was changing oil and oil filter every 2500 miles. I did the same with the Mobil 1. We used the Mobil 1 from about mid November through the first of March when we switched back to Motorcraft. Did this for several years.
The reason: had to have one vehicle that would start in the winter months.

No leaks, don't know about fuel economy (but I doubt it would ever pay for itself). As to wear, how much more engine life can you ask for? The secret to long life engines is change the oil and filter.

When we retired the vehicle with almost 500k, the cylinder head had never been off.

Jon.

[Toy4Chris]

Thanks for all the input guys. Synthetic seems to have way more plus than minus

[uneasyrider]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by carbking:
We put Mobil 1 in a vehicle with over 400k miles. But the way we got the vehicle to 400k miles was changing oil and oil filter every 2500 miles. I did the same with the Mobil 1. We used the Mobil 1 from about mid November through the first of March when we switched back to Motorcraft. Did this for several years.
The reason: had to have one vehicle that would start in the winter months.

No leaks, don't know about fuel economy (but I doubt it would ever pay for itself). As to wear, how much more engine life can you ask for? The secret to long life engines is change the oil and filter.

When we retired the vehicle with almost 500k, the cylinder head had never been off.

Jon. </div></BLOCKQUOTE>

What vehical was it and what was its use? Cyl. head was never off in that time... it wasn't a Toyota I'm guessing. That's a great testimonial but at ~$7/qt every 2,400miles I would have to get the pencil out on that one and see what the cost to benift ratio was. So why was the vehical retired at 500k?

[Toy4Chris]

Should I be using any particular weight with the synthetic oil???

[RPM]

Can't really go wrong with 10w30.

[Toy4Chris]

looks like 10/30 syn for me! Thanks guys

[Billy177]

used mobil 1 in my explorer since new. at 100k when i had to take off the valve cover to replace the timing chain tensioner. it looked brand new.

regular oil is not bad, synthetic is just better

[Toy4Chris]

whats the difference between 5/30 and 10/30???