73jst4fun

Ok, I'm going to switch to a synthetic oil. Besides the rumors of if you have an oil leak synthetics magnify any leak, what's the advantage and what's the eqivilent to say a 10w-30 or 10w-40 in a synthetic?

C3 Stroker

The viscosity wgts. are the same.....I use 10w-40 Royal Purple. Most magazine dyno tests show about a 5 HP gain (peak) over regular oil. I had to re-tighten my intake manifold bolts when I made the switch,..it does try to find its way out.

Hershey

I switched over to Castrol Full synthetic a few months ago and have been very pleased. I have a 150,000 mile engine and have developed no leaks. You know an engine with that many miles has a few internal noises, but they seem quieter now and I feel safer knowing that I have better protection for my internal parts. Hershey

chevymans 77

The two top full synthetics are Mobil 1 and Amsoil. You can check with any oil forum on the web and you will quickly find this out. I prefer Amsoil due to the fact there oil is more specialized for its service plus the extended drain intervals are nice to. There is a supporting vendor for Amsoil here on the forum.

Neal

Easy Rider

Check out - Royal Purple!

I put it in my '69. Had an ol' time Corvette mechanic working on it. He put a stethoscope on it and said he could not hear anything - not a lifter, not a rocker, not a bearing - nothing!

Oh yeah, it was running when he listened to it!

It is expensive stuff, but when I saw some bearings and races run under similar conditions (in racing engines) with two different oils, I was sold.

C66 Racing

Thanks Neal.

I've got a short description of some of the benefits of synthetic buried in this discussion on my website:
What is Motor Oil?

AMSOIL Synthetics come in these weights (among others) near or matching 10w30, 10w40:
AMSOIL SAE Synthetic 10w30
AMSOIL SAE Synthetic High Performance 10w40
AMSOIL Synthetic 5w40 European Motor Oil

Yellow73SB

I dont like synthetics when your running high rpms and the oils is getting hot it turns into almost water.

Gordonm

Not mine. I was running some high rpms this weekend at the autoX 4000 to 7000rpm and my oil pressure stayed fine. The temps were at around 190 which is hot for my car. Even when the synthetics "thin" out they still provide better lubrication than dino oils. I know the Nascar boys are running like 0w 15w. That has to be like water and those engines survive some pretty high rpms all day long.

I rum Mobil 1 10w30 in mine

PRNDL

so Subdriver, are you selling this stuff? A few mouse clicks got me to an online store, $75 for a case of 12 qts, but where do I sign up for the forum discount!!!!


oh, and to address the original question. 68 bigblock, my last oil change i went synthetic for the first time, and used Castrol (not the high mileage formula) for the simple reason there was a rebate that turns out I couldn't get in other words, I'm a cheap SOB! No noticeable benefits, but no leaks either. Only problem is, I don't know when to change the oil!!! I know it lasts longer.... but how long??

73jst4fun

Well you know I don't run any high rpms.. ..I've tried the Amsoil rear end fluid from Carlisle a few years back, so he told me "you won't need the posi-additive" wrong....Amsoil does make good products. I'll try the Mobil 1 or the Royal Purple, they sell it at Pep Boys and other local stores..........Gordon, the new gauge is on the way....

Gordonm

GDaina

Synthetic

smooth-rider

Be carefull off synthetics. I put amsoil 0w30 in my 99 Silverado that didn't get driven all that much and now I have lifter noise. What happens is with synthetic that sits for long periods of time like 1-2 weeks at a time the water or moistier whatever seperates from the oil alot faster than with regular oil and can lead to parts in the engine developing rust. I live in Minn. so the changing climits is inherant to moistier. Don't get me wrong I love synthetic but I learned a lesson on what vehicals to use it in. Just my 2cents

C66 Racing

Dropped you a PM.

LFZ

I don't mean to hijack the post, but while we're on the subject..after running a new engine on dino..when do you start to use synthetic?

GDaina

Don't know if you have your facts right or not, but one of the advantages of synthetics is that viscosity doesn't break down in high temps, unlike dyno oils.

GDaina

After a reasonable break in time, about 500 miles

AD2VET

I put Mobil 1 in my C3 quite a while back and it leaked pretty badly but didn't have a problem with fossil oil. I've got 192K on it now and it just uses a quart between oil changes (5K w/Castrol). Of course I only run Mobil 1 in the C5.

Red73

Mobil 1 in the vette, my truck and my wifes car.

GDaina

Yup, that's the problem with synthetics, they find leaks when gaskets are old and brittle. Fossil oil is more forgiving in that area.