Use what you want. You will get different opinions from everyone.
The API rating is a minimum acceptable standard. There are better base stocks and some additive packages provide better protection but are more costly. So oils using better base stocks and superior additives are going to cost more. They exceed the minimum API standards and provide better protection.
If you are using a 15W-40 diesel oil or a 20W-50 racing oil in your street car to get the protection you need you are getting less fuel mileage, less HP and increased cold start up wear. You also have an additive package that is not the most suitable for your needs. If you do some research you will find very few oils for gasoline engines that are not break in oils or racing oils that have enough ZDDP for flat tappet engines. Some that claim to don't when tested. Most don't list the zink levels anywhere. The extra cost of the Amsoil is mostly offset just in fuel savings, it is the correct weight, has the ZDDP needed for older engines and independent testing shows it provides better protection against wear so to me it is a no brainer. For an extra $30 a year Amsoil 10W-40 High Performance goes in my $8000 engine. By the way, I have a roller cam.
Here is some information about base stocks. They can be Group 1, Group II, Group III, Group IV. Going from the cheapest to the most expensive. Group V is reserved for additives and are the most expesive to produce
http://www.pecuniary.com/faq/oil-base-stock.html
Some cheaper oils use Group I or Group II Base stocks. These are less refined, inferior in performance and break down faster than the higher groups. Group III are sometimes labeled as synthetic or synthetic blends even though they are not a true synthetic but are further refined. Group IV are true synthetics. Group IV oils are more stable, less suseptable to oxidation, Have better cold cranking charactoristics and better resistance to viscocity breakdown than the others. Those that say all oils rated the same API or SAE rating provide the same protection are either misinformed or uneducated.

 

mako, you using thier oil filter also? amsoil says 15,000 miles or 1 year. would work for me since i run out of time not miles. what is the price per quart with the preferred customer price? what do you think a good break in oil would be. my solid flat tappet cam 489 will be firing up next week.

 

FWIW, I have both opinions and some practical experience with both the helmet subject and the oil subject

I've done a lot of single cylinder off-road bike racing at fairly high levels over the years and these are my observations:

Helmets - since I was a small child (started riding when I was six), I could only afford cheap helmets. Being a daredevil of sorts (jumping over 100' doubles & the like - on ATVs no less), I've had my fair share of crashes.

The only concussion I've ever received was delivered in a very minor crash in a cross country (forest trail style) race at relatively low speeds --- with a Shoei (i.e. very expensive) helmet. It was my first "expensive" helmet in over 20 years of aggressive riding and racing.

I've always wondered from that day forward if the helmet's "superior" construction was what caused it. I've personally found data since then suggesting my hunch was correct. I've since retired the helmet and went back a nice, but cheaper helmet --- only recently have I purchased another expensive lid, an Arai, mainly because of it's light weight & good reputation. Luckily I have not had any sort of significant crash, but rest assured if I do get a concussion in it from a what I would rate as a mild crash, it will be my last expensive helmet.

On to oils

In my experience, if you have an engine that stresses the oil, there is a difference. However, typical liquid cooled engines do not stress oils to this level.

Air cooled engines are a different matter, and a high compression, high revving, hot running air cooled engine can substantially benefit from a heavier weight & synthetic oil. I ended up settling in on Mobil1 15w50 for a couple reasons - although it may not be the highest quality group 5 synthetic, it is good quality group 4 PAO stock - highly available & reasonably affordable. It was "good enough" to get the job done and it was easy to obtain whenever you needed it. AMSoil is another example of a good group 4 PAO oil. If memory serves me correctly, Royal Purple, Motul, Klotz, and others are group 5 ester oils - the really good stuff - but even they're overkill for the air cooled race engine.

On the other hand, I also have liquid cooled race bikes that run over 14:1 compression, wicked cams, and spin upwards of almost 13,000 RPM with very short skirt, single ring pistons. Even these engines do not stress the oil enough to seem to make a difference.

From what I've seen, the big difference in modern oils (and mostly conventional vs synthetic) is how they handle outside of normal operating range temperatures, both cold and hot. In my air cooled race bikes, I could break down any conventional oil I tried in a couple hours. The synthetics lasted much longer. How do I know I was breaking down the oil do you ask? When it happens, the engine will tend to blue smoke on decel - when the oil is changed it is very thin. The smoke on decel will cease for a little time after a change. It took much longer to get to that point on synthetic - longer than what would generally even think of going between oil changes.

So, anyhow --- run synthetic if it makes you feel better or you want to extend your oil changes a bit, otherwise I've not seen any difference even in my demanding liquid cooled race bike engines between numerous oil types I've tried. Air cooled engines that are run hard are a different matter though....

 

I would break it in with dyno oil, Brad Penn, Joe Gibbs, Valvoline VR1 (Racing oil) and Break in additive, Comp cams or Redline. I would run this and dump the oil after break in and run the same again for 100 miles, dump it and go with the Amsoil with no additive. At this point your rings should be seated and the cam is broke in. Cut the filter apart and check for metal. I don't use Amsoil filters. I use Wix filters. The Amsoil is $8.50 a quart. Not a lot higher than the Joe Gibbs or Brad Penn oil. Way cheaper than saying "I should have used the right stuff" when the cam dies or a bearing spins.
What a lot of people are not taking into account is a lot of corvettes are driven harder than your typical daily driver even though they don't get as many miles put on them, a lot of these motors have two or sometimes three times as muck power as they came out of the factory with and in a lot of cases the redline is 1000 or even 2000 RPM higher. When you get on it hard or rev it higher it subjects the main and rod bearings and cam to lifter interface to a lot more friction and pressures they would ever see stock. Then you need more protection than the oil recommended for your car when it was new will provide.
JMHO.
I am sure others will disagree.

 

Most diesel oils carry both S (service or spark rating) and C (commercial or diesel rating). I believe Rotella carries CJ-4/SM . SM is the highest available standard for passenger vehicle. CJ-4 is the highest rating for a diesel engine.

 

All SM rated oils are less than 800 PPM of Zink and Phosphorous per new EPA requirements. All flat tappet engines need at least 1200 PPM of both.
Amsoil 10W-40 high performance has 1400 PPM Z & P.
Good protection for high spring pressures and faster ramps of modern grind flat tappet hydraulic and solid lifter cams.
As I said you will get a different opinion from almost everybody on this subject.
Use what you want.
I will use what I want.

 

I love a good oil thread. Lots of good points and opinions. And yes, buy what works for you; it's your car and your money. The current 15W-40 Rotella T has approximately 1200 ppm of zinc and 1100 ppm phosphorus. Regarding Amsoil: it is certainly good stuff. The top Amsoil products do not carry an API rating, this allows them to formulate (improve) their product without requisite testing. And yes, startup is where most wear occurs, primarily due to lack of oil from drain back. That's why it is important to give the engine a chance to warm up. Anyways, that's my opinion. Perhaps one day my L36 and 65 442 will have roller cams... Enjoy your cars.

 

Soo, a Gen I SBC with roller cam would work just fine with "modern oils" ie. lower ZDDP levels, right? Would there be any advantage in using high ZDDP oils in such an engine?

 

Me too. I can't wait to see all the real world field data come streaming in that substantiates the claims of the clenched-fist table pounders above. I am sure am tired of listening to marketing BS and theory.

 

Mike, Are you looking for actual test results comparing almost all leading motor oils? http://www.ctslube.ca/Docs/compare.pdf

 

No, not more marketing cr*p, I've seen a lifetime's worth of that. I'm looking for real world long term test by unbiased consumers, with a sufficient number of data points that a reasonable trend can be seen.

I did this for many years in the aviation field, 'real world' rarely matched theory and almost never a marketeer's wet dreams. One of my studies resulted in the withdrawal of type approval on an oil being produced by a major OEM who pushed the 'more is better' silliness.

The oil bidness is just as full of hype as is beer, soft drinks, bottled water, you name it.

The average SBC runs for about 150,000 miles before needing an overhaul. It always has- a very reliable and durable machine that survives in spite of owner neglect or over enthusiasm. There's no evidence that zoomy boo-teek oil makes them last any longer. Sorry.

 

We're all passionate about our cars. That's great. If we all held the same opinions, life would be pretty boring. Oil threads and thermostat threads rock!

 

Most gasoline engine oils over the years have had the zinc content in the oil reduced. That is why for break in most engine builders recommend a zinc additive. If you want to maintain the zinc level in your oil for its added lubrication properties try a mix of diesel engine oil (high zinc content) with your gasoline engine oil.

I haven't tried it yet myself but will try it my next oil change. A friend of mine runs 3qts. diesel oil to 2qts. gasoline engine oil in his 400hp 355ci and that motor runs excellent.

 

there are 3 good oil threads on another site (chevelle site). they actually sent oil off to be tested and posted the results. the summit racing oil was tested to 1800 zinc mix. i think summit has rebolted another oil but i forget the original name. anyway, several good threads there and they back it up with certified test results from 3 different labs.

 

Do you have a link that you can post?

 

This not marketing hype paid for by Amsoil. It is the results of ASTM testing that only Amsoil choses to post because of the results. ASTM is the largest independent testing and certification body in the world. I would consider ASTM as unbiased as it gets. That engine that runs 150,000 miles could very well last much longer with better protection especially at startup and under extreme conditions. In an engine seeing extreme use better protection could make the difference between finishing and catastrophic failure. If it don't fail you wouldn't know that it was because of the better protection so I don't really know how you would get that information. Superior hot and cold temperature performance, reduced oxidation and acid formation and better long-term wear protection are all proven facts shown in the charts compiled by ASTM.
http://lshim.com/comparison.htm

 

Those are not 'proven facts' they are 'lab results'.

I was attempting to stress the point that lab results do not always match field results. I can quote multiple examples where the exact opposite of lab predictions happened in the field- specifically with the 'more is better' line of thinking.

Even if the lab is correct, and there's no negative effects with the supposed benefits of this oil, how would you know if it's of any real value? Using a trailer hitch as an example, a person can install one with a 2,000, 5,000 or 10,000 lb. capacity. What's the point of spending the big bucks on the 10K unit if the maximum hauled is 1,000 lb?

The SBC has been around for over half a century and achieved a remarkable durability record from day one- back when oils were very simplistic from an refinement and additive point of view. How come there's no data available that indicates they last longer now even with 'miracle oils' than they did 50 years ago?

 

I am 51 years old. I do remember back in the late 60's early 70's very few engines lasted 100,000 miles without oil consumption, manufacturer oil change intervals were 3000 miles and engine warrantees were 12,000 miles. These engines used the manufacturers recommended oil. A SBC with 200,000 on it that didn't use oil was unheard of. You would see them going down the road with the blue cloud following them. Now you are seeing 200,000 miles or more average life expectancy from the SBC with little or no oil consumsion between oil change intervals of 7,500 miles and warrantees of 100,000 miles. My brother has a 94 5.7 3/4 ton GMC truck that has over 300,000 hard miles on it with no issues. He has run Amsoil in it since he bought it with over 150,000 miles. The computerized FI and spark distribution, and better tolerances and rings have a lot to do with it but the oil quality also has a lot to do with it.
Synthetics are the manufacturers recommended oil for every modern high performance vehicle made for good reason. The top automotive engineers in the world have figured out that warrantee repair costs are reduced and service life extended using them. Like the dyno oils, some perform better, are of better quality with better additives than others even though they meet the same minimum API standard. Same goes for synthetics. High quality Group V protective additives are very expensive to produce and the oils that use them will cost more. They exceed the minimum standard by more than others.
I look at it like going to the doctor. Every GP has the same license to practice medicine. My GP was the validictorian in his class at Loyola and has that certificate proudly displayed on his wall in the waiting room. That same graduating class also had a doctor that has a practice somewhere that graduated last in his class. He doesn't display that achievement on his wall. He meet the minimum standards. He has the same certification to practice medicine though.
I know there is nothing I could say or link I can post that would change some peoples minds on this. There is no scientific evidence that exists that would. To them I say use what you want and good luck.
If it doesn't fail how do you prove it was the oil?
If it does fail how do you prove it was the oil?
The only logical way to make an informed decision is through comparing results of scientific testing. This is the same testing done to obtain the API rating in the first place.
I will use what I believe is a better product for the minor overall difference in price. Considering the cost of a quality high performance rebuild today or for those wanting to keep their original unrestored engine in top form this is a small price to pay.

 

OK, for grins and giggles, I'll play the game your way. You claim that SBCs last longer now because of better oils. Great. Which ones? You quoted a few examples and attribute their longevity to the brand of oil.

I know of many engines with similar mileage that never got a drop of miracle oil, some of which also got pretty badly abused and ignored- and survived nonetheless.

If we're going to go outside of the an*l retentive obsessive compulsive world of Corvette owners and start talking about Joe average driving his pick'em up or Mom's soccer van, do you really think many go out of their way to buy boo-teek oils? Gimme a break. They put in whatever the local garage pours in or whatever is on sale at Costco.

So how do you explain that so many engines last so long with the majority of owners not giving a rats a*s about their oil or without obsessing over maintenance?

Oh- and by the way, you lost all credibility with the 'high performance cars all use synthetics' cr*p. I can see mine outside the window as I type this and NO cars manufactured by this OEM use synthetic.

 

Not meant to argue with anyone, but...
People take better care of their cars today.
Machining is far better (closer tolerances), gasket technology is far better.
Oil and oil filters are far better.
Heck, radiators, electonics and tires are far better.
And slant sixes ran 200K back in the day, even with shoddy services...
Aint it cool when we are all right?