ckwhite

For years I have used Unocal Royal Triton motor oil in all my vehicles, not just because I worked for Unocal, but because I've read all the statistics which show it to have the best properties. More recently, given the difficulty of finding Royal Triton anymore, people are telling me I should switch to a synthetic oil like Pennzoil, Amsoil or Mobil 1. Aside from reportedly being able to extend my oil change interval (which I probably won't do) why should I spend the extra $ for a synthetic. C'mon guys - give me some facts or personal experiences other than "because I've always used it"..

RollaMo-LT4

The biggest benefit from synthetic, is resistance to breakdown from heat, and the extended change intervals you mentioned.

If you haven't been using synthetic in the car up to now, I don't really see any compelling reason to switch just because others are telling you to do so.

I am using synthetic in my '96 because it came from the factory with it.
I am using synthetic in my Harley because of the air cooled engine and resistance to breakdown from heat.

I am still using conventional oil in my Silverado though.

Edit: Using synthetic in the Camaro SS too, because that is what it shipped with, and what the factory recommends.

Aaron Keating

One, the oil will maintain it's viscosity properly throughout the operating range of the engine far better than standard oil will, two due to the superior lubrication properties, it will also run cooler than standard oil, and as a by product of both of these your engine will make just abit more ponies. A full synthetic swap front to rear of the car usually gains about 8 to 10 horse power (not bad for just a routine maintenance item eh?). It also will gain you a fraction better gas mileage as well.

It also will gum up your engine far less than standard oil. Every engine we've ever pulled pans on etc the one with the synthetic was cleaner around the valve train, and on the bottom end of the pan.

There's a series of Car Craft articles about it too, http://www.carcraft.com/techarticles...ventional_oil/ There are some other ones they did over the years in hard copy and I'll see if I can dig up a digital version for you.

Everything I own including the lawn mowers get Synthetic oil at this point. Mind you the synthetic I'm putting in the mowers has already been used in the car (I run it through a couple of coffee strainers and then a sock), but its' still synthetic, and imo the mower even runs better on it than new dinocrude.

GKK

1) Engine stays cleaner.

2) Viscosity is a lot more consistent throughout the different heat temps.

3) longer oil change intervals.

4) Just Better!...

Paul Workman

As already said:

All of those things mentioned, except the real reason$: The viscosity stability increase enabled GM to eliminate the oil cooler on the 92+ MY (base) Corvette. Oh, and of course, Mobil kicked in "a little" cash to have their logo decal glued under the hood too.

That asside, the ZDDP levels are especially important too, for flat tappet motors. Someone said when GM went to roller tappets; somewhere in the 80s, but for sure the LT5 is a flat tappet motor, so to have the best of both worlds; viscosity stability AND ZDDP, the Amsoil AMO 10W 40 has both. (Amsoil makes another synthetic too, formulated especially for flat tappet motors - the details allude me just now...)

P.

ThatVguy

Having trolled BITOG forums for a few years, in a stock vehicle, or even a moderately modified car, there's really no reason.

GL5 conventional oils are as good as synthetics from not that long ago, the heat resistant properties and even varnish protection they provide are measured against extremely tough regulations and testing for the engines of today that use Turbocharging and D/I, so an old SBC is simply not going to tax it's capability that much. The *only* reason I use M1 in my vette is because The cadillac gets M1, and so does my beater, because I run extended OCI's in those vehicles, and buying just 1 brand/ weight of oil for 4 different cars is pretty easy. Once I start sampling the L98 I'll run extended OCI's in it too.

If you've run a conventional and want to continue using one, or you're looking for short fixed intervals, I'd start using some PYB (pennzoil yellow bottle), it's an excellent oil, and it's a BITOG forum favorite. Excellent shear stability, good amount of TBN, and it'll take a 7.5K OCI without issue.

rws.1

Synthetic basestocks have better resistance to shear thinning and oxidative thickening, meaning they stay in grade longer.
They also have higher levels of detergent to keep your engine cleaner , longer.
Finally they provide better boundary layer lubrication.

PLRX

Joe C

i see you're running a, pretty much stock L98 - any, conventional, QUALITY, motor oil is just fine for a daily driver. granted, synthetics are superior, but for your application, they are just over kill. i don't know how often you change your oil, but anywhere in the 3K-5K range, with a quality filter is fine. the use of synthetics in non-factory spec'd engines is a bunch of hype! best thing to do is follow your owners manual for the oil type and viscosity index. do that, and that L98 will outlast you!!! in my old 85 (now my son's), we've been pretty much running castrol gtx, 10w30 with delco filters for 17 years, and 150K plus miles. ran a compression check a couple years ago, and the readings were textbook - somewhere in the 165-170 range, average. oil consumption - less than 1/2 qt between changes. around here, it's not so much what's the best oil for my application, but it's the "nothing's too good for my baby" syndrome - whether needed or not. granted it's your, and everyone else's money, and you can do whatever you want - just giving my 2-cents.

WW7

All the answers above are correct, and I also use synthetic in my 89, mainly because it handles high temps better.. But,,regular dino oils work just fine in any of our engines and many on here still use them.
The best reason I can think to use synthetic, is for just an extra $10.00 a year you know you have the best oil availible in your motor........WW

C66 Racing

Here is AMSOIL's input on the benefits of synthetics:

"Conventional lubricants are refined from crude oil. Contaminating elements such as sulfur, nitrogen, oxygen and metal components such as nickel or vanadium are inherent to crude oil and cannot be completely removed through the refining process. The oil refining process separates the various types of molecules in the oil by weight, leaving molecules similar in weight but dissimilar in structure.

Synthetic lubricants, on the other hand, are chemically engineered to form pure lubricants. Synthetic lubricants contain no contaminants or molecules that don't serve a designed purpose. They are made from molecules that are saturated with a higher percentage of carbon- hydrogen bonds, leaving fewer sites to which other, harmful molecules can attach and attack the molecular composition of the oil. In addition, their smooth, uniform lubricating molecules slip easily across one another. In short, synthetics' versatility and pure, uniform molecular structure impart properties that provide better friction-reduction, optimum fuel efficiency, maximum film strength and extreme-temperature performance conventional lubricants just can't touch." (emphasis in bold mine)

Not addressed above, and not really related to synthetic vs. non-synthetics is the topic of anti-wear additives. The current API SN spec still has the band 600-800 ppm phosphorus.

Unfortunately, phosphorus, along with zinc, in a compound called ZDDP, or or zinc dialkyl dithio phosphate, forms an oil's primary anti-wear additive. The reason behind this is that phosphorus slowly poisons the cats and prevent the catalytic exchange that allows them to function properly. To ensure auto companies could meet the EPA's 100k+ emissions requirements, the API has slowly been dropping the limit on phosphorus.

So, any oil labeled to meet the current API SN spec will be limited to 800 ppm max phosphorus. This impacts how well it will be able to perform in anti-wear, such as might be seen in your bearings under heavy load.

There are oils that get around this such as "high mileage" oils and these synthetic products from AMSOIL:
AMSOIL Z-ROD 10w30 Synthetic Motor Oil (Product Code ZRTQT)
(zinc – 1440 ppm, phosphorus 1320 ppm)
AMSOIL SAE Synthetic Premium Protection 10w40 (Product Code AMOQT)
(zinc – 1378 ppm, phosphorus 1265 ppm)

More than happy to get AMSOIL products for forum members at dealer wholesale pricing, about 25% below retail, via the AMSOIL Preferred Customer Program. Drop me a PM if interested.

Joe C

here's a little something i've found on-line about this subject...

H P Bushrod

nickgost

On a 92+ (LT1) C4 Full Synthetic Oil is REQUIRED!. Instead of an oil cooler GM decided to use better heat transferring oil.

Z51JEFF

Ive got a 91 ZR-1 and the cam chains naturally rattle upon first start up.I was told that Amsoil Synthetic oil would help quite down the cam chains.Im a skeptic when it comes to things like this but Amsoil did just what Ive read it would do,Im sold on the stuff.One other thing Im sold on,the Bosch oil filters for the LT5.The oil filter in these cars are inverted with a check valve thats supposed to help the filter retain oil.The Bosch filter retains the oil like the others failed to do.This motor takes 9 quarts of oil so an oil and filter usually runs about $110.Not cheap but wont buy anything else.

C66 Racing

The two GM standards listed above, 6094M and 4718M, have been superseded by dexos1. It was commonly believed that to meet the standard for the Vette (4718M) a synthetic was required - not specifcially called for in the spec but needed to meet the spec's requirements. Now with dexos1 the waters are muddied. Dexos1 is debatably a more stringent spec than the U.S. industry standard API SN. While GM says that dexos1 superseded 4718M, it is also debatably not more stringent than 4718M. It is commonly believed that to meet dexos1 a semi-synthetic is required. Better?

aklim

BEFORE anyone goes past 3000 for an oil change, get it tested first. That way, you KNOW how far you can go. If the tests say "You have about 3000 miles more to go", you can add that to the number you have and go that far. Otherwise, it is a SWAG at best.

cv67

Look up 540rat in the C3 section

Some pretty good information with real world testing results

1963SS

Here's a real life reason why I use it. I have a 30' Wellcraft Scarab and it has two big blocks in it. I used to leave the marina and go about 40 miles up the river at about 4000-4500 RPM. When I used Dino oil I would leave the marina with 60 pounds of oil pressure and after about 15 minutes of hard running the pressure would settle in to around 40-42 PSI.

I switched to Mobil 1 and the oil pressure never got below 55 PSI no matter how hard or how long I ran the old boat. This is just a real life demonstration of everything that's been said above.

ThatVguy

synthetic oil based on 20 year old specifications.

I think you'll find most GL5 name-brand conventionals of today would pass test requirements of what would be considered 'synthetic' oil from 2 decades ago. 'conventional' oil of today are highly refined organic stocks with very good heat and varnish/deposit control. They have to be, since the engines they're designed to be used in are far more demanding than a SBC, and they run upwards of 7-10K mile OCI's.



On a stock, healthy engine that does not see daily track use, in TPI, CF, Or LT1 flavor, I see no reason, at all, to do anything less than 5K changes, even with any name-brand conventional.

There's plenty of UOA testing on BITOG on various SBC's to support this, as are flavors of every engine from every car manufacture that essentially ruin the theory that anything less than 5K is generally wasteful.

The only reason you should do that short of an OCI is if you suspect fuel or coolant contamination, or if you don't manage to put that many miles on the car annually.