Shell Rotella T4 10w-30

[Bruins_Fan]

Is Rotella T4 10w-30 still a good motor oil choice for the Corvair? I only ask as I know the oil companies sometimes change formulas, ie. reduce ZDDP, etc.

I've been using Valvoline VR1 10w-30 since I bought my Corvair in 2018, but it's getting a bit pricey. I'm down to 4 quarts, so after the next change (soon), I'll probably make the switch,

Thanks!

[steve57]

The ongoing oil question, what to use. I use full synthetic 10w30, currently Mobil 1. Previous owner had years of records using whatever bulk 10w30 oil the local Chevy dealer put in it. Some swear by Rotella or Amsoil. Good luck figuring it out!

[66vairguy]

Is Rotella T4 10w-30 still a good motor oil choice for the Corvair? I only ask as I know the oil companies sometimes change formulas, ie. reduce ZDDP, etc.

I've been using Valvoline VR1 10w-30 since I bought my Corvair in 2018, but it's getting a bit pricey. I'm down to 4 quarts, so after the next change (soon), I'll probably make the switch,

Thanks!

The "Rotella" formula has been changed a number of times over the last few decades to meet the diesel emissions standards. At one time it was reported that FORD banned it from use in their diesel truck engines until Shell "fixed" the "new" formula to meet Ford's requirements! Hard to guess how good it is now. NOTE: at one time Rotella was stated as "Can be used in diesel or gasoline engines". That statement was DELETED from the Rotella site last time I looked years ago.

About ZDP (or ZDDP). It was rarely added to oil until the late 1950's!!! Engine camshafts didn't self destruct (at least no more than normal). When oil change intervals were increased (to save the consumer money -- or "Our cars are less expensive to maintain") camshaft issues arose during WARRANTY. The big oil companies under pressure from the auto manufactures found adding ZDP helped compensate for "worn out oil". One issue -- too much ZDP is CORROSIVE. So the formula is precise - don't use additives!!!

So what to do now? It's really simple -- change the motor oil every 1,500 miles or once a year (which ever comes first) like in the days BEFORE ZDP was added to oil. Most hobby cars rarely see more that 1,500 miles of use a year. ZDP is an anti-scuff additive for when oil film breaks down (worn out). Note today's name brand quality oils are so much better than the 1960's formulas that any QUALITY 10W30 motor oil is fine IF you change it at 1,500 miles or once a year (which ever comes first). If the engine is operated for only short periods the oil will contain moisture and acids and should be changed BEFORE the car is stored for Winter. Just my humble opinion on what I've read. You can look up the history of ZDP (ZDDP) online.

[miatawnt2b]

I just saw at Costco today that Kirkland has a 15w40 diesel oil for $31.00 for 3 gallons. Seems like a good deal so I researched it a bit on bobistheoilguy. I think it's a winner for me.
-J

[bbodie52]

Although it is somewhat pricey, I have come to believe that these Royal Purple motor oil and gear lube products are a good match for the Corvair engine and manual transaxle.

HIGH PERFORMANCE ENGINE OIL (WITH SYNERLEC®)

HPS is recommended for use in gasoline and diesel automotive, commercial fleet and stationary industrial engines. Royal Purple® HPS® Series motor oil is specifically formulated to maximize performance and meet the demands of high performance and modified engines. HPS is recommended for vehicles no longer under manufacturer warranty and for those seeking a higher level of performance and protection. Royal Purple HPS oils are fortified with a high level of zinc / phosphorus anti-wear additive and a generous dose of Royal Purple’s proprietary Synerlec® additive technology. These unique formulations enable HPS oils to outperform leading synthetic and conventional lubricants in both gasoline and diesel engines.

PERFORMANCE ADVANTAGES

• Exceptionally high film strength for dramatic reductions in engine wear and reduced engine heat to extend the life of your engine
• Improved sealing between the piston ring and cylinder wall maximizes horsepower and torque and optimizes fuel economy
• Exceptional oxidation stability extends oil life and allows for more miles driven between oil changes saving you time and money
• Advanced synthetic solvency reduces engine deposits and keeps engines clean
• Outstanding wear protection for valve train components, including performance roller lifter and high lift flat tappet camshafts and lifters
• Superior corrosion protection

https://www.royalpurple.com/product/hps ... motor-oil/


This synthetic gear lubricant appears to support both hypoid differentials and, unlike GL-5 lubricants, is safe for "yellow metal" synchros.

Special gear oils are required for hypoid gears found in Corvair differentials because the sliding action requires effective lubrication under extreme pressure between the teeth. ... They are considerably stronger in that any load is conveyed through multiple teeth simultaneously. By contrast, bevel gears are loaded through one tooth at a time. Hypoid gear oil is formulated with extreme-pressure (EP) additives to protect and operate effectively with hypoid gears.

EP additives which contain phosphorus/sulfur compounds are corrosive to yellow metals such as the copper and/or brass used in bushings and synchronizers.

A traditional GL-4 gear oil of any given viscosity has about ½ of the level of sulfur/phosphorous additive that would be in the GL-5 product, so the bond is not as strong, and therefore can be peeled off without peeling a layer of brass (or less brass). This means that the GL-4 product provides a little less extreme pressure protection, so in the differential of a high-powered car, it would not be the ideal product in the differential. To understand this need we should be aware of the fact that the differential is where the final torque is applied to the wheels (in most applications)...

---Some cars (including later Corvairs) came with military specs instead of API gear oil specs. So we should consider that MIL-L-2105B is an equivalent to GL-4, and MIL-L-2105C, 2105D, and 2105E are GL-5 gear oil lubricants.

Tue Nov 07, 2017 11:32 am

... DO NOT USE Redline MT-90 in a Corvair transaxle. Redline's site specifically states that MT-90 is NOT approved for hypoid gears (differential). So it is NOT acceptable for use in a Corvair transaxle since protection for the ring and pinion differential gears is inadequate. Redline does make a modified GL-5 lube that is suppose to work with brass synchronizers called - 75W90 NS GL-5 and states it's approved for transaxles with brass parts. NOTE: Redline NS GL-5 is different vs. their GL-5 which is NOT approved for transaxle use.

Basically, Corvair transaxles share the lubricant in the transmission portion and the differential portion. So it is necessary to compromise and select a gear lube that will protect the hypoid gears in the differential and not harm the "yellow metal" synchronizer components in the manual transmission. A good quality GL-4 Hypoid gear lubricant (SAE 75W-90) in your Corvair manual transaxle is the way to go.

HIGH PERFORMANCE GEAR OIL (WITH SYNERLEC®)

Max Gear is recommended for truck and automotive differentials, outboard motor lower units or in rear axles or manual transmissions requiring an API fluid. Max Gear is a high performance automotive gear oil designed to provide maximum protection to heavily loaded gears while increasing power throughput through the drive train. Max Gear virtually eliminates both gear and bearing wear—even under severe squeeze film conditions caused by extremely high loads, sudden shock loads or low RPMs. Slippery, synthetic molecules not only reduce wear and friction but significantly increase Max Gear’s cold weather fluidity and lubricity, making it the ideal choice for vehicles operating in cold climates. Gears run smoother, quieter, cooler and longer without overhauls. It is noncorrosive to both ferrous and nonferrous metals.

PERFORMANCE ADVANTAGES

• Maximizes horsepower
• Extends gear and bearing life
• Reduces operating temperature
• Lower coefficient of friction
• Superior corrosion protection
• Separates rapidly from water
• For use with open, limited-slip and locking differential
• Contains limited-slip friction modifier

https://www.royalpurple.com/product/max_gear/

[66vairguy]

I just saw at Costco today that Kirkland has a 15w40 diesel oil for $31.00 for 3 gallons. Seems like a good deal so I researched it a bit on bobistheoilguy. I think it's a winner for me.
-J

I used to be a believer in a thicker viscosity to improve camshaft life, BUT a known oil expert on the CCF (Richard Widmark) finally convinced me a "good" engine that is NOT worn out should use 10W30 viscosity. I looked at all the data and a 15W40 is too THICK and actually more harmful for a healthy Corvair engine than the correct 10W30. Of course if the engine is worn out then a thicker oil keeps it going a while longer.

I try to go by the facts, but sometimes intuition is hard to overcome. I finally admitted my oil "assumptions" were wrong. I've been using low ZDP 10W30 in my rebuilt Corvair engines for years and they have been trouble free.

[66vairguy]

I've been using Valvoline VR1 10w-30 since I bought my Corvair in 2018, but it's getting a bit pricey. I'm down to 4 quarts, so after the next change (soon), I'll probably make the switch,

Thanks!

CCF oil expert Richard W. evaluated Valvoline VR1 years ago and surprisingly the formula sold in Europe was different then the U.S.A. version. Richard considered the Euro version a superior lubricant, BUT NOTE racing oils are typically low on "detergent" additives (detergent additives counteract sludge build up) because detergent additives inhibit lubricating properties of motor oil. Simply put, if you are going racing, then VR1 is worth the cost, but for a car driven normally it needs to be changed more often than regular Valvoline to drain contaminants out, or they can accumulate in the engine.

[Bruins_Fan]

I've been using Valvoline VR1 10w-30 since I bought my Corvair in 2018, but it's getting a bit pricey. I'm down to 4 quarts, so after the next change (soon), I'll probably make the switch,

Thanks!

CCF oil expert Richard W. evaluated Valvoline VR1 years ago and surprisingly the formula sold in Europe was different then the U.S.A. version. Richard considered the Euro version a superior lubricant, BUT NOTE racing oils are typically low on "detergent" additives (detergent additives counteract sludge build up) because detergent additives inhibit lubricating properties of motor oil. Simply put, if you are going racing, then VR1 is worth the cost, but for a car driven normally it needs to be changed more often than regular Valvoline to drain contaminants out, or they can accumulate in the engine.

Yes, I recall that. I actually messaged him before I started using VR1 and he confirmed it was fine, also mentioned the detergent additives. As I'm changing oil at least every 300 or so miles, it's not really an issue. My main gripe is the rising price (along with everything else!).

[bbodie52]

...Yes, I recall that. I actually messaged him before I started using VR1 and he confirmed it was fine, also mentioned the detergent additives. As I'm changing oil at least every 300 or so miles, it's not really an issue. My main gripe is the rising price (along with everything else!).

Unless your engine suffers from excessive piston blowby of contaminants into the crankcase, changing the oil every 300 miles or so would seem to be excessive and unnecessary. Perhaps the higher cost of a good-quality synthetic oil could be justified, offering fewer oil changes while providing the desired added engine protection and demanding less-frequent oil changes, while satisfying concern for minimizing engine wear.

The development and implementation of the Positive Crankcase Ventilation (PCV) system also did a lot for reducing crankcase pollution of the oil and eliminating the development of engine sludge.

[Bruins_Fan]

Yeah every ~300 miles does seem like alot, but that's only 1-2 oil changes per year. Of course, the car is parked all winter long up here in New England. I generally do an oil change around the start of driving season, and another at the end. Some years I might skip one, but never go beyond 10-12 months between oil changes.

[66vairguy]

Yeah every ~300 miles does seem like alot, but that's only 1-2 oil changes per year. Of course, the car is parked all winter long up here in New England. I generally do an oil change around the start of driving season, and another at the end. Some years I might skip one, but never go beyond 10-12 months between oil changes.

Your response was great and proves one needs the compete picture before making assumptions. Since I drive my car year round, albeit not much, I only need to change the oil once a year at about 1,000 miles. However, a car should NEVER be put up in storage for the Winter with old contaminated oil in it. Before storage the best thing you can do is take the car out for a long drive wiht some miles at highway speed to heat up the oil (unlike engines, oil takes a while to heat up), then change the oil and store the car for the Winter.

One of the issues with "hobby cars" is they don't get driven much. Even engines in great shape have enough piston/ring blow-by to contaminate the oil, especially with water vapor that can turn corrosive when it combines with other chemicals in the oil.

The lack of mileage I put on my Corvair is why I don't spend the money on high-end oils, especially full synthetics. Full synthetics have the advantage of tolerating more heat without deteriorating. Great for racing, or in turbo engines that are driven exuberantly! Otherwise they don't lubricate much better and certainly don't stay any cleaner than a basic quality 10W30 motor oil. Since I don't race my car, and it's not a turbo, I don't spend the extra money on a racing or synthetic oils.