Originally Posted by kcsa75 (Post 4331897)

I had the oil changed in my 72 today. I was planning to go with Valvoline Synthetic, but the manager told me it was "too old for sythetic." I didn't push the issue as I have no issue with conventional Valvoline but afterward I got to wondering if I'm missing something. I understood that the sythentics were fine for older engines.

Any thoughts?

Originally Posted by spike38 (Post 4331960)

There are a lot of myths about using synthetic oils in older vehicles.
Mobile 1 has a whole site dedicated to these myths. But it all boils
down to, All vehicle benefit from using synthetics, Not to say there is
anything wrong with traditional oils. Just that synthetics last longer,
And keep your engine cleaner. If you think you have a lot of sludge
in your motor, I would change it a little sooner after switching over,
The first time ( it will clean your motor). Then use recommended times.

Spike:smoke:

Originally Posted by Longhorn Man (Post 4332176)

there's a few reasons not to run synthetic... but no real good reasons. (other than burning and leaking oil as mentioned)
The zink comment above holds no water, becouse there are no 'over the counter" oils on the market (including rotella) that contain enough for non roller motors.

Originally Posted by OhOneWS6 (Post 4332406)

That is a matter of opinion. Valvoline VR1 still has zinc and is available over the counter. For an all out high performance engine more zinc may be desired but for a stock to mild street flat tappet motor it is plenty.

Originally Posted by treveiger (Post 4332510)

Check this out, thats what im putting in my truck.
http://www.amsoil.com/storefront/amo.aspx

Originally Posted by OhOneWS6 (Post 4332406)

That is a matter of opinion. Valvoline VR1 still has zinc and is available over the counter. For an all out high performance engine more zinc may be desired but for a stock to mild street flat tappet motor it is plenty.

Originally Posted by 1969stepside (Post 4333822)

valvoline vr1 20w50 is still high zink till the end of next year

Originally Posted by 70cst (Post 4332645)

http://lubriplate.com/webstore/default.aspx

This is what I use...:chevy:

Originally Posted by So.Cal.Super (Post 4334534)

As far as the Zinc debate goes.
Zinc has been drastically cut down or almost eliminated from today’s conventional oils due to catalytic converter failure. I would like to know what the conventional oil of the 60’s levels was. For this I have researched and can’t seem to find the Data any more the Hearsay.

Originally Posted by http://www.jalopyjournal.com/forum/showpost.php?p=3711603&postcount=17

(Bob, who is now retired, was one of GM's Top lubrication engineers)

Engine Oil Mythology
Bob Olree
GMPT – Fuels & Lubes

All of these myths have a common theme; newer oils are bad. And this brings us to the latest myth – new “Starburst”/ API SM engine oils are bad for older cars because the amount of anti-wear additive in them has been reduced. This one has gotten big play in the antique and collector car press lately. The anti-wear additive being discussed is zinc dithiophosphate (ZDP).

Before debunking this myth we need to look at the history of ZDP usage in engine oil.

ZDP has been used for over 60 years as an additive in engine oils to provide wear protection and oxidation stability. Unfortunately, ZDP contains phosphorus, and phosphorus is a poison for automotive catalysts. For this reason ZDP levels have been reduced by about 35% over the last 10-15 years down to a maximum of 0.08% for “Starburst”/API SM oils.

Zinc dithiophosphate was first added to engine oil to control copper/lead bearing corrosion. Starting in 1942, a Chevrolet Stovebolt engine with aftermarket copper/lead insert bearing connecting rods was the standard oil test . The insert bearings were weighed before and after test for weight loss due to corrosion. The phosphorus levels of oils that passed the test were in the 0.03% range.

In the mid 1950s Oldsmobile got in a horsepower war with its Rocket engine against the Chrysler Hemi. Both companies went to high-lift camshafts and both got into camshaft scuffing and wear problems very fast. There were three solutions. Better camshaft and lifter metallurgy, phosphating the camshaft, and increasing the phosphorus level from ZDP up to the 0.08% range. Another outcome was a battery of industry wide “Sequence” oil tests. Two of theses tests were valve-train scuffing/wear tests.

Knowing that this higher level of ZDP was good for flat-tappet valve-train scuffing and wear, some oil companies dumped even more in thinking that they were offering the customer even more protection. However it was soon learned that while going above something like 0.14% phosphorus might decrease break-in scuffing, it increased longer term wear. At about 0.20% phosphorus the ZDP started attacking the grain boundaries in the iron, resulting in camshaft spalling.

Later in the 1970s, the ZDP level was pushed up to the 0.10% phosphorus range as it was a cheap and effective antioxidant, and increased antioxidancy was needed to protect the oil in Cadillacs pulling Airstream trailers from thickening to the point of not pumping. Recently, the need for this higher level of ZDP for protecting the oil from thickening has been greatly reduced with the introduction of more modern ashless antioxidants that contain no phosphorus.

Enough history, now getting back to the myth that “Starburst/API SM oils are no good for older cars. The argument put forth by the myth believers is that while these oils work perfectly well in modern gasoline engines equipped with roller camshafts, they will cause catastrophic wear in older engines equipped with flat-tappet camshafts.


The “Starburst”/API SM oil standards were developed by a group of OEM, oil additive company, and oil company experts. When developing any new engine oil standard the issue of “backward compatibility” always comes up, and indeed the group of experts spent a lot of time researching this issue. Various oil and additive companies ran “no harm” tests on older cars with the new oils. No problems were uncovered.

The new specification contains two valve-train wear tests. One is the Sequence IVA Test which tests for camshaft scuffing and wear using a 2.4L Nissan single overhead camshaft engine with slider finger followers. The wear limits were tightened from the previous oil specification which contained a phosphorus limit of 0.10%. The second is the Sequence IIIG Test which evaluates cam and lifter wear. A current production GM Powertrain 3.8L engine with the valve train replaced with a flat tappet system similar to those used in the 1980s is used. The only reason that this test engine uses this older valve train design is to insure that older engines are protected. All “Starburst”/API SM oil formulations must pass these two tests.

In addition to the protection offered by these two valvetrain wear tests and the new testing which was conducted on the formulations containing lower levels of ZDP, a review of the knowledge gained over the years in developing previous categories also indicates that no problem should be expected. The new “Starburst”/API SM oils contain about the same percentage of ZDP as the oils that solved the camshaft scuffing and wear issues back in the 1950s. They do contain less ZDP than the oils that solved the oil thickening issues in the 1960s, but that is because they now contain high levels of ashless antioxidants that were not commercially available in the 1960s.

Feb 13 2007