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Discussion Starter #1
Have a question for all the C3 Guys and Gals. Anyone running Synthetic oil in their SBC? I bought a case of Royal Purple and a Fram filter for it. Will that reduce friction or should I buy some Z-Max? I am getting the engine rebuilt mabey or a crate motor but just needed to change the oil for the time being and wandering if I am going the right way. It stills runs super strong. But I need to keep the maintenance up on the engine. :thud:
 

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a case of royal purple? no you should not use it, but if you send the oil to me i will use it for you :laughing: there seems to be mixed thoughts on using synthetic oil, i think mainly due to that it could cause an oil leak in an older motor, and that it should not be used in a new motor for break in.
my car had been sitting for 13 years before i found it in january of this year,i am running mobil synthetic oil in it now for the past 5 months and 300 miles and no leaks.
but i am also having a new motor built for it,and the builder said no synthetic for the first 300-500 miles, and then he suggested Royal Purple 10-40 XPS Extreme synthetic after that.
he said a new motor will not break-in or it will have a hard time breaking-in on Syn oil.
I like syn oil,have used it for years with no problems,and i agree with not using it for break-in, use conventional oil.
hope this helps.

Kevin.:D
 

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IMHO, synthetic oil is a good thing- on an engine that's broken in. It reduces wear, which is good, but if the rings haven't seated they probably won't with synthetic oil. It's too slick. One it's broken in, say 5000 miles,( and that's an arbitrary number) then the synthetic is no problem. On a real hi mileage engine, leaks are a possibility, because the viscosity of synthetics is so low. Not every engine will leak, but it is possible. I'm running syn oil in my daily driver, and have since it passed 25000 miles. No leaks or consumption between changes and that's at 10000 miles.

I can't see any problem with you changing your engine now to syn oil, but be prepared for consumption and/or leaks. Seems that every engine responds differently to it. I worked for a guy that changed his fleet over to it and 3 of 9 trucks started using it like no tomorrow. The rest were fine. Go figure. He switched back to dino and no more problems.

:cheers:
 

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Discussion Starter #4
Well, I bet you would like thayt fur me ta send ya that case of Synto. I got leaks right now with the darn regular oil. Might rejuve it for a while . Like you I want another engine and then pull this one out and redo it for the simple fact that it is 195 HP and is really good on gas. But a C5 might get me better gas mileage if I find the right one. But not selling the 2 C3. Just wanna do a mabey off frame with the 79 . And stop using it for driver.

I bought that on E-bay for 79 bucks for a case of that oil you mentioned. Gonna try it then. Thanks for have that, that will do just fine message. :laughing:
 

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LOL...Kevin hit the nail on the head with this one. Find 100 people and you'll have 100 different opinions on syn vs dino. Note that GM installs Mobil 1 synthetic in their new Vettes right from the factory. My 1998 C5 had a label under the hood stating that GM recommended Mobil 1 be used in the engine. I've used Mobil 1in my 2004 Chevy Silverado (325 CI engine) since the first oil change. No problems at all. My wife has a 2003 Explorer and I use dino oil in it. Mainly because that's what was used in it all it's life. If I was around when she bought it brand new I'd be installing Mobil 1 in it for it's first oil change and every change thereafter. I also had two 2002 Chevy Monte Carlo SS cars and used Mobil 1 in their V6 engines. No leaks in ANY of these cars. That theory about using dino for break-in and syn afterwords has pretty much fallen by the wayside. I would use syn for break-in and forever after that. What I would NOT do is switch back and forth from syn to dino and back to syn. You might confuse the engine if you do that :laughing:

Dep
 

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Discussion Starter #6
Another good thread. I have a friend who runs the C3 Registry and she absolutely told me she refused to run any thing but Dino in her C3. Mine has a bad cam, and it leaks from the rear seal and the rear end. But that is caused from not driving it enuf. I must admit it. I drive it to town, it sits for a couple hours and no leaks. I come home, put it on the jacks (stop tire rot) and 24 hrs later she is drippin again. By the time the next month rolls around I gotta take the air cleaner off to start her and she runs fine after that. Kikkin my own Azzzzzz for not fixin the darn thing now that I have the bucks to do so. And this 195 ain't no sloutch. She will get up there in a hurry if need be. She will also burn the tires in second gear with that shift kit. I do not know what she would do with synthetic oil and her block rebuilt. I tell you I had many SBC and BBC and all I did was add oil. Never changed it and the damned things ran like a top with one quarter size drop of oil under the oil pan. I know what not to do. Put some Detergent oil in an old injun. Clean um out rat now. But I got tired of workin for Mosquito control down here next to the swamp. Good thang it was just a ford. No mo Foads. Chevy dictates puttin one on. And I listen. I think I might try that anyway. I am needed either to have the motor rebuilt or a crate. Or if she keeps changin her mind a number order for sale on E-Bay or Trailer Queen status and rot in hell. Thanks for the help on the Synto. I been runnin her since 02 on cheap oil that I won on a "Poker Run" and she ain't missed a lick yet. God help me, cuz if she runs any better I am gonna just have to keep the original motor in her. Ok, I will try it. :agree:
 

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... The viscosity of synthetics is so low. ...

:cheers:
That is why I never use or recommend synthetics in our engines. Our engine tolerances (in most C3 engines) were engineered for straight viscosity oil. Anything else the oil is too thin.

JMHO
 

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That is why I never use or recommend synthetics in our engines. Our engine tolerances (in most C3 engines) were engineered for straight viscosity oil. Anything else the oil is too thin.

JMHO
I would agree with this...IF...the engine were a factory original engine that had not been rebuilt. Since most C3 owners have either rebuilt or replaced their engines, I'm not sure this holds true any more. I don't know of ANYONE still using straight weight oil in their cars, other than guys that only drive at the track. Multi-grade oils offer protection at both ends of the spectrum and flow freely at all temperatures. This is not 1969 and oil technology has made gigantic improvements since then. JMHO :D
 

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synthetics have a different viscosity than mineral oils? 10w40 = 10w40

10W40 means it's a multigrade oil that has a 100*c viscocity similar to an sae 40 weight single grade oil so that it passes the viscosity test at that temperature (w in multigrades means winter btw, not weight) and it's a 10W base oil that passes the viscosity 0*C test. How does this 10W base oil become a multigrade 10W40? The multigrade oils use something known as viscosity index improvers to give it that multi viscosity. These are polymers that do something nifty when warmed up. In cold environments they are coiled up like springs and thus have little to no effect on viscosity, when they warm up they uncoil and stretch out and DO affect the viscosity. The oil will thin out much less this way.

So simply put, you start w/ a 10W base oil and add VII to stabilize the thinning of the oil and do some testing, if it passes the test for 40W ti's a 10W40, if it also passes the hot temp viscosity standard for a 50 classification, then it's a 10W50, same for cold.. if it passes a 5W viscosity test it's a 5W40...and so on. So 10W50 can do anything that 10W40 can do and more. a 10W50 oil will not thin out more @ 100*C than a 50W SAE oil would do @ 100*C, remember this started as a 10W base oil
Since operating temps matter most a 10w40, 5w40 0w40...these are all SAE 40 oils in that environment, no matter what the prefix says, the only difference is the viscosity @ colder temps and thus the lower number will pump easier. There's no such thing as a multi viscosity oil, they are multi grade because they pass a whole range ofgradings for oil weight classifications, they do however not have multiple viscsities (as this is always defined @ a certain temp)

Out engines were built for straight oils because that's all they had. Does that mean you have to run it now? NO! A 10W40 can do ANYTHING a single grade 40W can do and a lot more.

As for the break in and sysnthetics, this has to do w/ the base oils and additive packages, the synths have a much higher shear resitance and heat and load capacity before the oil fails. This also means that it's much harder to seat rings with those oils and that's why you use minerals. The use of single grades eliminates the chance of problems caused by high contents of VII that can bake onto top rings and cause problems there, especially during break in. This is a problem with mineral oils as they require quite a bit of VII to give a large viscosity spread and this can lead to potential problems.
 

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I use "synthetic blend" oils, mostly castrol or valvoline 5W40 oils in both DDs. I noticed some oil "crud" in the filler cap and under the valve covers, not enough to worry about but some.... you don't see this buildup with synthetic oils :thumbsup:
 

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That is why I never use or recommend synthetics in our engines. Our engine tolerances (in most C3 engines) were engineered for straight viscosity oil. Anything else the oil is too thin.

JMHO
do you mean like straight 30wt or straight 40wt or straight 50wt?? I don`t have a Corvette owners manual here but I would disagree with that statement, every street driven car/truck I have ever owned requested use of a multi weight.
....redvetracr
 

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The only time I have seen a single grade oil requirement was in the owners manual for a 81 formula 301 turbo, it called for straight 30 wt, the ring gaps on those engines are so big they smoke like crazy when cold
 

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do you mean like straight 30wt or straight 40wt or straight 50wt?? I don`t have a Corvette owners manual here but I would disagree with that statement, every street driven car/truck I have ever owned requested use of a multi weight.
....redvetracr
My 74 manual says to use 30wt oil with temps above 40* F and 5W-30 in Canada. :laughing:

It does show multivis oil as being usable using 10W and 20W with multiple grades.

My 77 F100 manual shows straight vis as well.

Dep, the engine design is still the same. The bearing clearances are the same as the original and on and on.

Every time I put multivis oil in a '60's and 70's engine, rebuilt or not, my oil pressure (on the gauge) drops from 5 to 10 PSI.

Multivis oil is made with polyimers which control the viscosity. The polyimers make up a relativly large amount of the "oil". Polyimers add no lubrication properties what so ever.

JMHO
 

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there is no such thing as a multiviscosity oil, read above. Whenever used in manuf. literature it's either misinformation or a bad choice of words.
 

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Again, everyone has their own opinion and knowledge and experiences.

I find that if you change your oil every few thousand miles....religously, or in my case, twice in the summer (once at the start of the season and again in july) you can use whatever oil you want. I use a multivis with Lucas Oil additive and my last two oil changes were so clean that the oil still had some transperency.
 

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My 74 manual says to use 30wt oil with temps above 40* F and 5W-30 in Canada. :laughing:

It does show multivis oil as being usable using 10W and 20W with multiple grades.

My 77 F100 manual shows straight vis as well.

Dep, the engine design is still the same. The bearing clearances are the same as the original and on and on.

Every time I put multivis oil in a '60's and 70's engine, rebuilt or not, my oil pressure (on the gauge) drops from 5 to 10 PSI.

Multivis oil is made with polyimers which control the viscosity. The polyimers make up a relativly large amount of the "oil". Polyimers add no lubrication properties what so ever.

JMHO
Well I sure don't understand it. My Dad was a BIG user of 10W30 oil most of his life and NEVER had a problem with leakage or anything else. And that was with cars from the late 60s right up into the 90s from Ford, GM, and Mopar. Ford recommended 10W30 for MANY years. Last time I used straight weight oil in anything was a lawnmower back in the 60s. Even my new Sears lawnmower uses multigrade oil. NASCAR and NHRA are all using multi-grade oil in their race engines (with the exception of the blown nitro engines).

About oil pressure gauge readings:

"The key words in the previous post of mine which you described were "...ACTUALLY NEEDS...". In other words, if an engine is set up so loose that it "ACTUALLY NEEDS" 15W-40 oil to maintain proper oil pressure, that could mean that it's set up too loose for dependable, long-term street service.

All 1969 Corvettes, including L-88s, should operate with normal oil pressure using 10W-30 weight oil. However, for ambient temps above 20 degrees F, 10W-40 or 20W-40 were approved engine oil viscosities. In my opinion, the latter 2 viscosities would be the preferable ones for use in an L-88. But, the L-88 engine should maintain normal oil pressure with 10W-30.

L-88s used a standard volume, high pressure oil pump. The high pressure pump was designed to "overcome" or compensate for some of the "looseness" in the engine set-up. Idle oil pressure shoud be about 20-25 psi. Keep in mind, however, that the original in-car oil pressure gauges are rather notoriously inaccurate. Usually, they read 5 to 10 psi LOW. To determine what actual oil pressure that your engine is running at, you need to temporarily install an accurate, high quality test gauge."

http://www.ncrs.org/forum/archive12.cgi/noframes/read/76512




This from the Mobil 1 website:
Myth: Mobil 1 will leak out of the seals of older cars.
Reality:
Mobil 1 does not cause leaks. In fact, new Mobil 1 was tested in dozens of industry standard and original equipment manufacturers (OEMs) tests to prove its seal performance. It is fully compatible with the elastomeric materials from which all automotive seals and gaskets are made. If an older engine is in good condition and does not have oil leaks, Mobil 1 provides the same advantages as when used in a new engine. ExxonMobil recommends taking measures to repair the leaks, then using Mobil 1. ExxonMobil also recommends following the automobile manufacturer's manual for the proper oil to use.

From the NASCAR website:

Ever wonder about synthetic oil and how it compares to petroleum based oil? Well, the word "synthetic" means it's made with a combination of chemicals, so synthetic oil is "designed" while crude oil is "refined."

Synthetic oil contains a uniform molecular construction that's created to perform consistently under the harshest circumstances. It also starts out contaminant free, which is impossible for traditional petroleum based oils.

Starting the engine is tough on all of the internal parts, which is why many people appreciate synthetic oil's adhering quality. Even after the car stops, there is a film left to coat the engine parts, protecting them during the next start up.

Finally, because synthetic oil doesn't break down, it doesn't have to be changed as often. Certain manufacturers claim oil change intervals as high as 25,000 miles, justifying synthetic oil's high price for some motorists.
 

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Also, thicker is not better, no matter what your mechanic or engineer told you. 20W-50 has 40% more viscosity (resistance to flow) at operating temperature than 10W-30. This means that your engine has to work 40% harder just to move the oil around inside your engine. An engine with thick 'oil' produces significantly less power, uses more fuel, produces more emissions and runs hotter, all contributing to shorter engine life. A thinner oil can more easily and quickly be 'pumped-up' to the critical parts of the engine, takes less energy to move it around, helps the engine to produce more power, less emissions, better economy. And the engine will last longer too! This has been proven numerous times in test after test, by many different and highly respected testing facilities. Unfortunately, the rule that 'you can't teach an old dog new tricks' prevents many 'experts' from accepting the facts. Indeed, when I was a kid, it was Castrol GTX 20W-50 in every car I had! In the years since, I have been working in the automotive lubrication industry, (15 years now) have been on the engineering boards of several major motor oil manufacturers. I feel lucky that I was able to 'see the light'.

http://www.boss302.com/oil.htm
 

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no such thing huh. well i guess the oil manufacture is wrong then.
http://www.pennzoil.com/products/motor_oil/multi_vis.html

and to think pennzoil has had it wrong all these years.


Yes to think that, they have it wrong. Or better put, they use the wrong terminoligy.
Viscosity is measured, usually in centistrokes @ a certain temperature. it is IMPOSSIBLE have 2 different viscosities. What they mean is it has a viscosity gradient over temperature, meaning the viscosity index improvers modify the oil in such a way that it does not thin out like the base oil normally would but it thins out less, and this is classified for instance as a 10W40 being a 10W not thinning out more @ 100*C than a 40W oil.


Here, straight from the valvoline site:

Multi-Viscosity
One oil manufacturer claims that "some people in the industry use multi-viscosity as if it means the same thing as multigrade. An oil cannot be multi-viscosity, but it can be multigrade by meeting the viscosity requirements for SAE 30, 40, 50 or 60 and one of the sub-zero "W" viscosity requirements. At one time, some oil companies labeled oils SAE 10W, 20W30—as if the oil could be 10W and 20W at the same time. This is impossible because 10W is measured at -20 degrees C and 20W is measured at -10 degrees C, which eliminates the multi-viscosity theory."
 
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