Hi ahondadriversnightmare, 73Delta88, All
Actually, it's just the opposite. Most plastics (as well as the synthetic rubber used in tires) are petroleum based products.

Synthetic lubricants were developed in Germany during WW II, to make up for their lack of Petroleum.
If synthetics were not equal to or better than petroleum, that war would have been very short.

There is only one difference between them, and it's what makes one superior to (and more expensive than) the other.
Not true. Mostly good information there. It mirrors my own philosophy: Follow the manufacturers recommendations, and KISS.

Just understanding the difference between the two is enough to sort fact from fiction, no matter where you read or hear it.

Does anyone know what that difference is?

Regards, Norm

I will take a guess, although I've made an ass out of myself already. Conventional oil is distilled and refined from crude oil. Synthetic oil contians the same natural ingredients as conventional oil (plus whatever other additives they put in) except the ingredients are chemically combined, and free of impurities. I don't know if that's the difference, but I know that it's a difference.

Hi schippa2, All
As I stated in my previous post, synthetics were developed because of the lack of access to oil.
Additives will be the same for both types, and will vary from brand to brand.

I should have been more clear in my question. ops:
Does anyone know the difference, in the finished products, that would cause the lubricating characteristics of one to be superior to the other.
It's a small difference.

Regards, Norm

something to do with the molecules, in synthetic there all the same better lube and heat disapation

in conventional oil theres different formations of molecules

I use Mobil products in all of our cars, partially because it's what we sell at work, and also because I've had excellent luck with it against thermal breakdown compared to some other brands. Standard oil, no synthetics.

In regards to Synthetic oil, a few things should be kept in mind. I may have missed Norm or someone mentioning this, but normally synthetic oils aren't generally recommended in high mileage(over 100,000 miles) engines unless the car has been run on synthetic for a period of time prior to this. The reasoning for this being that synthetic oils and lubricants tend to be more "slick", for lack of better words, and tend to find every leak, crack, crevice moreso than a conventional type oil, possibly causing oil leaks that were not previously noticed with conventional oil. Also, it is possible that when using synthetic oils in high mileage engines, oil consumption and burning may happen for the same reasons. I've had customers on several occasions come in with higher mileage engines wanting to switch to synthetic, and after doing so, ended up going back to a conventional oil due to oil leakage, burning, and consumption that they didn't have with a conventional type oil. Just another couple things to keep in mind.

Hi speedy266, strokercutlass, All
Close enough.
Think of two flat mating surfaces that create friction when rubbed together.
Put a bunch of ball bearings between them and there is no more friction.
Now replace them with an equal number of bearings of varying sizes and the friction increases.

The molocule sizes are random in petroleum, and uniform in synthetics.
Please elaborate.
It would be time to change from synthetic to standard because of the burn/leak factor. Have you seen it first hand, or is it what your customers have told you?
Customers have a lot of reasons for saying a lot of things. Sort of like the internet.

I've heard that synthetic oil is priced higher because it will not leak or burn as much as petroleum. Someone probably believed it.

Regards, Norm

I use Castrol GTX in my car. I changed my oil today, and I used Castrol GTX High Mileage with a Purolator filter. 138,000 miles baby!

Over the years I've tried several brands in my higher RPM performance type engines, and in regards to sustained oil pressure readings after a run, or over several thousand miles, as well as oil viscosity and cleanliness at time of oil change, I've had the best luck with either Mobil or Castrol GTX oils. Since we began selling Mobil products, I switched to Mobil and never went back...



Actually Norm, I have seen this first hand on several vehicles which have passed through the shop, the majority of which being at or over the 100,000 mile mark, as well as discussing it with our oil rep. The general consensus was.... at the 100,000 mile mark most lubrication related damage is most likely already done, so what is the significant gain of switching from a petrolem based lubricant to a synthetic based lubricant at this point in mileage....I could justify it myself at a lower mileage point, bue going by a general standpoint of a standard 3,000 mile interval range oil change averaging roughly $23 and a synthetic oil change at 6,000 mile intervals averaging $45, the cost is roughly the same on a higher mileage engine, and with oil consumption and leakage being a possible side effect, where is the gain? Of course it will differ greatly depending on each vehicles previous maintenance and such, but from an overall standpoint, does the end justify the means at this point in mileage?......

Remember back when Slick 50 became so popular? The manufacturer specifically recommended that it should NOT be used in vehicles which had surpassed 100,000 miles, due to internal mechanical wear and damage that had already been done.

I have considered trying a 20W50 synthetic in the '72...however, being that it's tolerances are somewhat loose, I'm not sure whether the gain would be significant enough to justify it, especially if oil consumption came into play.

Hi strokercutlass", All

I don't disagree, however, my question is: Have you seen first hand (before and after) that synthetics themselves caused leaking and burning, and that going back cured it?

Because there is no logic (I'm being charitable) in changing from a conventional oil at a high mileage, I suspect many people have changed to synthetic to improve a leaking and/or smoking condition, and when it didn't happen, it was easier to blame it on the oil.

BTW, if Slick 50 worked as advertised, wouldn't it still be popular?

Brando: I need a smiley for "tongue in cheek".

Regards, Norm

What about just getting the used oil from McDonalds when they get done frying thier frenchy fries?????? pretty cheap...

Seriously, I have always used "regular" oils, I have my favorite brand, I like the way it smells.

Hi OldsGuy, All
As a matter of fact, oil from deep fryers has been used as diesel fuel (bio-diesel?).

Regards, Norm

Hey Norm...let me rephrase a bit, as I may not have been clear enough. I have seen several cars come in which we regularily service at the required intervals which have always been run on "X" brand conventional oil, without significant smoking or oil consumption. After switching over to the same "X" brand synthetic oil, it was noted that the engine used more oil between oil changes, as well as more noticeable oil smoking out the tailpipe and breather. On these particular cars, switching back to the previous conventional oil showed a drop back to less oil consumption and less oil smoke and blowby.

I suspect that many people switch over to synthetic oil due to marketing hype moreso than anything. With the trend of people keeping their vehicles longer and putting more miles on an already high mileage engine, I believe they're trying to do whatever they can to extend longevity. However, the thing they don't fully understand is that at that mileage, synthetic oils don't provide a great benefit over standard oils for the difference in cost, unless the car has lived it's life on synthetic oil. I'm regularily seeing cars at the 125,000 to 150,000 mile mark now, where 3-4 years ago the average miles were in the 75,000 to 100,000 mile mark. People are driving further to work to find good jobs, keeping their vehicles longer due to increased costs on new vehicles (hell, I wouldn't pay $22-25,000 for a new entry level vehicle either), diesels are up in the 200,000 to 300,000 mile mark now, as a new diesel truck is in the $30-50,000 range for a fully equipped one. Why wouldn't the oil makers try to sell to this market? Max life oils, high mileage oils, synthetic....anything they can do to tap into a new market of consumer...

I really do enjoy these intellectual discussions you and I have, Norm It's nice to know I'm not the only one out there who gets overly technical about things at times

Hi stroker, All,
I'm glad you didn't mention leakage. My biggest problem is trying to figue out how (under equal conditions) one of two liquids of equal viscosity, could leak and the other not.

Next time I have nothing to do, I'll see if I can find out what changes there have been in motor oil technology since I was in school.
I know the sales rhetoric is still the same.

My Cutlass has 127K, and just out of curiosity I think I'll try a change to synthetic. It doesn't leak or smoke and if it still didn't it wouldn't prove anything. I might even do a before and after at the local Strip if it doesn't leak too much.



Regards, Norm

I saw a video in my environmental science class about some car that Volvo made sometime in the eighties. It was made of plastic and lightweight metals, and had a three cylinder diesel engine. They showed this guy go into a supermarket, buy a bottle of some kind of cooking oil, dump it into the fuel tank of the car, and drive off. That is some weird, wild stuff!