switch to Mobil 1 for my '70 LT1?

[adam schorr]

I've been reading the benefits of synthetic oils recently in an article published in one of the popular covette mags i subscribe to.

I'm wondering if I should switch the motor oil I use in my stock, NCRS top-flight, '70 LT1.

The engine was re-built (about 3-5,000 miles ago) with hardened valve seats to 11:1, and runs great on 100 octane un-leaded.

Particularly with cold winter approaching, I wonder if @ next oil change, I should make a switch from traditional (10w-40) oil, to Mobil 1 or other synthetic?

Are there any potential downsides? The article mentioned fears of leaks, or other maladies are mythes and should NOT be a problem. Others have mentioned:

quote: "there are fewer zinc extreme pressure additives in synthetic (you NEED! this for a flat tappet camshaft.)"....use the Valvoline "not for street use" racing oil (at least 2-3 qts mixed) for my "vintage" LT-1 Vette to protect my camshaft."

what should i do?

thanks!
adam

[Duke W.]

Re: switch to Mobil 1 for my '70 LT1?

Have you ever read about the benefits of HD diesel engine oil - API service category CI-4? Do you know that the additive package in a motor oil is more important than the base stock oil? Do you know that the addtive requirements for vintage engines are different than modern engines? Do you know that CI-4 oils have a higher concentration of detergent, dispersant, anti-wear, and anti-corrosion addtives than spark igntion oils (current API spec SL) regardless of base stock? Do you know that the concentration of these critical additives have been reduced in modern spark ignition oils because modern engines don't need as much and their combustion byproducts are not kind to catalysts? Do you know that vintage engines that see low mileage accumulation can potentially suffer more internal damage from corrosion in the long run than wear? Do you know that some synthetic oils for modern spark ignition engines have NO ZDDP anti-wear additive, the chemical that keeps the forged pistons from scuffing? Do you know that the primary advantages of synthetics is their lower oxidation rate, which allows for longer mileage (NOT TIME) change intervals, and their greater viscosity index allows for better oil flow at subzero temperatures? Do either of the above two services apply to your Corvette? (BTW, new Corvettes can go up to 15K miles before the oil monitor says it's time to change the oil, but to maintain your warranty, the oil must be changed after 12 months regardless of mileage or oil life remaining.) Did not know that contrary to popular myth, synthetics are NOT "more slippery" than conventional oils?

The following web site is a good place to start to learn more about motor oils, particularly the API service categories.

www,api.org

It will probably be a cold day in hell before some "expert" writes an article in a Corvette magazine about additive packages and the different motor oil requirements of vintage engine that see low mileage accumulation versus modern engines that are run everyday, but that doesn't mean everybody can't get their own education.

Duke

[Donald M.]

Re: switch to Mobil 1 for my '70 LT1?

Duke, back on the subject of diesel oil API C1-4, I noticed at my local auto supply store that all these types of oil were of 20W-40 grade or thicker. I curently run 10W-30 in my 327/300 and have for the 23 years I've owned it. I would like to put in C1-4 oil, but the heavier viscosity puts me off. When referring to the oil viscosity chart in my owner's manual, it doesn't even show 20-40 wt. I live in FL. if that is any help.Thanks.
Don

[Duke W.]

Re: switch to Mobil 1 for my '70 LT1?

The most common national brands of multi-vis CI-4 is 15W-40. I buy Chevron Delo in gallon jugs at Costco or local auto parts stores.

New multigrades have been introduced since our cars were built, so they will not be in a sixties vintage owner's manual, but if you look at the viscosity chart in your owner's manual it probably says that straight SAE 30 is okay for ambient cold starts down to 40F; That's what my Cosworth Vega owner's manual says. (The SWC manual is tucked away.) 10W-30 is okay down to zero F, and a 20W-40 would be the same as far as cold starts are concerned as a 20W-50, which is okay down to 20F. The lowest ambient temperature that you expect to do a cold start determines the maximum first "weight number" - the one followed by the "W" in a multiviscosity grade.

40F is about the lowest temp I will ever see in So. Cal, so a 15W-40, 20W-40, or even a straight 30 would be okay, and I expect you will not ever do a cold start below 40 in Florida either.

Duke

[Michael H.]

Re: switch to Mobil 1 for my '70 LT1?

Duke,

I have a question. I really don't know much about todays oil but I wondered if adding a pint of GM EOS would bring the detergent additive ratio back up to somewhere near what the old oil was in the 60's or 70's. EOS was supposed to contain most of the detergent additives that the old formula had. Thanks

Michael

[Duke W.]

Re: switch to Mobil 1 for my '70 LT1?

I don't know if today's EOS is the same as yesteryear, but it is my understanding that it has a heavy does of anti-wear agents that are beneficial for breakin. I also recall that GM does not recommend it as a regular oil supplement - just for breaking in a freshly rebuilt engine. Too much additive can lead to deposit formation, especially if oil consumption is high, and some additive combustion byproducts can degrade catalysts on modern cars.

CI-4 oils have an excellent additive package for vintage engines including the ZDDP anti-wear chemical, and I don't think any additional addtives for normal vintage engine service are necessary.

The problem with modern SL oils, both mineral and synthetic base stock, is not detergent content, but many lack any ZDDP that is beneficial to keeping forged pistons from scuffing and flat tappet cams from going... FLAT!

Duke

[Michael H.]

Re: switch to Mobil 1 for my '70 LT1?

Ok, thanks Duke. I'll continue looking for the HD Rotella in a 10W30. Seems like no one carries anything lower than 20W40 or 20W50.

[Duke W.]

Re: switch to Mobil 1 for my '70 LT1?

I don't see any problem using a 20W-XX in Florida. Out here in CA Rotella, Delvac, and Delo are commonly available in 15W-40 in addition to straight 30 and 40.

I use 15W-40, which is okay for cold starts down to about 20F, which is considerably lower than I will ever see.

duke

[Michael H.]

Re: GM EOS

I'll try the 15X40 in the big block car. That motor seems to make the oil real ugly in just a short time. (typical big block)

Just got an email from a friend and he was telling me that the back of the EOS can makes mention of the fact that it replaces the detergents that are burned off or used up during operation between oil changes. It is thick, like STP, but GM never actually did recommended it as a viscosity improver, just a supplement.

Wish I would have dug out some of the original paperwork from GM on this stuff.

Thanks Duke

[adam schorr]

switch to Mobil 1 for my '70 LT1?

duke,
so, switching to HD diesel oil API CI-4 would be advisable? what viscosity?
Here in Connecticut, the winter temps get as low, or lower than 32 degrees F, (Zero degrees C). During the winter, i drive the car only for the sake of not letting it sit. short dirve to warmmit us, and back into the garage.
if i understand your second post correctly, what viscosity should i use during winter months? 10w-30? Summer?
thanks,
adam

[Patrick H.]

Re: switch to Mobil 1 for my '70 LT1?

Adam,

I use the 10W-40 "diesel oil" here in Michigan.

Also, I add Sta-Bil, top off my fuel tanks, and change the oil just before storage. I then let them SIT until mid April (heated storage at 50 degrees, most of my cars in a Car Jacket), as I have never found nor heard of any true benefit of the occasional warm-them-up-in-the-winter theory. And, I've never had a problem with them sitting. The potential damage from salt and dumb drivers far outweighs any minimal benefit.

If you don't take the car out and drive it for 20-30 min anyway, just sitting there running is not helping it.

Patrick

[Duke W.]

Re: switch to Mobil 1 for my '70 LT1?

First, you are ill advised to drive your car in the winter "just to warm it up". Many studies have concluded over the years that 80 percent of engine wear over the life of an average car occurs during cold start and warmup. If you don't WANT to drive it, don't drive it! You are better off letting it "sit", but there are some simple short term storage prep procedures you should follow.

1. Wash the car, vacuum the interior, detail as required.
2. Change the oil and filter
3. Drive the car for at least 30 minutes after the wash, and a full warm up after the oil change to be sure all trapped water is dried and the fresh
oil circulates thoroughly throughout the engine.
4. Pump the tires up to the maximum cold pressure listed on the sidewall or 35 psi, minimum.
5. Change the coolant and brake fluid if they will reach their two-year expiration before the end of storage.
6. Fill the fuel tank to capacity with fresh fuel
7. Disconnect or remove the battery and charge it at least once a month or leave a Battery Tender installed.
8. Protect the car from rodent damage with traps under the car and poison in the engine compartment, cockpit, and trunk.
Inspect for rodent activity, monthly.

Many ignore rodent protection and end up paying a steep price. BY FAR, the most common cause of storage damage is rodents!!! If you follow the preparation steps the chances of any mechanical damage or corrosion are near zero. The above assumes the car will be stored indoors, and, of course, it is a good idea to cover the car.

The clock does not run on fresh crankcase oil during winter storage, but it DOES run on brake fluid and antifreeze.

Come spring check TP and fluid levels and give the car a general inspection. Crank the engine for two five second periods to fill the fuel bowls, then go through the normal cold start by pumping the throttle once to add a pump shot and set the choke. Start engine. Since the oil is still considered zero time and mileage, you can drive the car for the entire driving season on this oil and change it again prior to the next winter storage.

Since you won't be driving the car in cold winter weather a 15W-40 CI-4 oil would be suitable, and it is acceptable for cold starts down to about 10F.

Duke

[Duke W.]

Stabill

I've heard some unfavorable anecdotal evidence about Stabill. I've been storing some of my cars for six months to one year periods over the last ten years and have never used it or any similar product. I can also report that I have had no fuel system problems.

As Patrick knows from his chemistry training, chemical reaction rates tend to increase exponentially with temperature, so winter storage in cool to cold temperatures will minimize any adverse reactions in the gasoline.

The shelf life of gasoline is generally regarded as about six months to a year, in mild temperatures in sealed containers and this is probably conservative. Car fuel tanks can be considered "semi-sealed", especially models that have evap control systems or a cap with pressure and vacuum relief valves.

Filling the tank with fresh fuel before storage assures reasonably long storage life, and a full tank minimizes the fuel's exposure to oxygen, which can accelerate gum and varnish formation. A full tank also minimizes the "vapor dome" that can cause condensation if the storage area temperature drops to the dew point or below.

I don't consider "Stabill" or like products to be a necessity for short term winter storage. It also probably won't hurt, but I question whether it is worth the price.

Duke

[Patrick H.]

Re: Stabill

Duke,

I've never heard much either way on the Sta-Bil. I use it, though, on my cars, mower, chain saw, etc and so far they all re-start in the Spring.

One of my friends lets his 68 Pontiac Firebird sit for years at a time between uses and it always re-starts, so there's probably more shelf life than 6 mos to gas.

Patrick

[adam schorr]

Re: switch to Mobil 1 for my '70 LT1?

thanks again. rodents? good advise. already baited the poison. installing new garage doors.
in past, i prepped and "stored" my '74 for 6 years before selling to buy the '70 in 2000. this winter's different b/c wife & i bought an actual house with a garage...as opposed to manhattan apartment with paid parking and lots of orange traffic cones for barrier. Manhattan garages are actually warmer and dry compared to some homes...all for $400/month :-(
my winter "warm-ups" are always 20-30 minutes of actual driving, and ONLY if the roads are clear, salt-free, after couple good downpours. the diesel oil sound like a simple, safe, and effective change for long and short term engine protection.