Oils today, both regular and synthetic, are usually sold in 5 quart, 1 gallon and quart containers. My BB requires 6 quarts as do many other engines. Is there a problem mixing brand names as well as weights ?Example, 5 quarts of Exxon 10W40 with 1 quart of Castrol 20W50 or any combination of any of the currently available oils - including mixing regular with synthetic. Does mixing different brands and weights compromise their additive package? Steve

 

None of what you propose will cause any problems, but why don't you use an API CI-4 heavy duty diesel engine oil? They have a better additive package than oils designed for modern spark ignition engines with catalysts. Your vintage engine will like the additional detergents, dispersants, anti-oxidation, and anti-wear additives. This has been discussed a zillion times.

Duke

 

Some folks don't like to mix oils, but I've yet to hear of any problems caused by doing so. And I don't know of any chemically based answer which would cause problems to arise. Lastly, if it could cause problems, I believe the owner's manuals would have precautions about mixing brands, weights, viscosities, or oils with different additive packages. I've yet to see any such warnings.

Don't doubt that you may get some other opinions, though. But these are my thoughts and observations.

 

I would like to go that route, what brand and weight do you reccomend and can I purchase at local auto parts store?

 

Duke, What you and others have stated about the API CI-4 heavy duty diesel oils is the way to go. But before I can make the switch I have to use up my inventory of various brands and weights that I have acquired over the past few years. These brands ( Exxon, Quaker State, Castrol, Valvoline, Cam 2, Havoline ) are all 10W40 and 20W50 and are not approiate for use in my newer vehicles. Therefore, I was going to use them up before the switch but was not sure about their ability to mix. I have heard that it was better to stay with one brand but never read anything that said you had to. By the way, what is your opinion on Marvel Mystery Oil ? Have you used it in either your gas or oil ? I have heard many good things about it but nothing documented. Thanks, Steve

 

I use Rotela 15-40, available at Wal-Mart in 5qt bottles as well as the single quart bottles

 

Menards sells the Rotella 15w40 as well in 5 qt jugs. You could work off your inventory by mixing 2 qts other with 3 or 4 qts rotella. Mix 1 qt thinner oil (10w40) with 1 qt heavy stuff (20w50). One note on the 15W40 - not suitable for use in very cold weather.

brian

 

HD diesel engine oil is API service category CI-4. Brand is not important. Select whichever bottle color you like best, flip a coin or buy the cheapest, or most expensive - whatever! The major national brands are Chevron Delo, Shell Rotella, and Mobil Delvac. There are also many house and off-brands. I like Delo. I don't know why. I just do. Maybe it was because back in the sixties I could bump the timing to 18 degrees with 103 RON Chevron Custom Supreme gasoline. Great stuff! There's a big Chevron refinery a few miles away from me, and I can buy Delo at Costco.

API CI-4! That's all that counts.

The commonly available multi-vis CI-4s are 15W-40, which is suitable for cold starts from about 10F to over 100F. I know that Delo is also available in 10W-30 if you drive your car at temperatures below about 10F, but I've never seen it in stock at any local outlets.

There is no harm in mixing any API service categories (including any "C-" or "S-") to include synthetic or mineral base oils. Basically all automotive motor oils are compatible.

Modern motor oil additives are all essentially the same. It's just that the current CI-4 oils and some older "S-" classifications have higher concentrations of some additives than modern SL or SM oils. Also, newer mineral oil base stocks have higher oxidation resistance than some of the older service categories, but that's not a reason not to use an older service category oil if you have some in inventory.(Actually, many "conventional" mineral based oils have some synthetic base in them to meet the minimum oxidation resistance requirements for all current API grades.) Oxidation of the base stock is a primarly cause of sludging, which is much less frequent nowadays than in the past. Some modern cars have had a sludging problem, and it's likely caused by either inadequate crankcase ventilation or too high oil temperatures in normal driving, and in most cases it may be due to owner inattention to proper change intervals for their driving habits.

My two modern cars have oil capacities of 4.5 and 6.3 quarts, respectively, and I use 15W-40 Delo for the last fractional quart with the even quarts of whatever API SL or SM 20W-50 I happen to be using, which is whatever national brand was on sale that last time I bought a case!

Back in the sixties the recommended oil change interval was 6000 miles or 60 days, but modern CI-4 oils on occasionally driven Corvettes are okay for a year assuming you drive a few hundred to a few thousand miles per year.

If you store the car during winter, change the oil just before storage. The clock doesn't run on fresh oil in the crankcase while the car is in storage. Since most of us probably drive our cars least in winter, a fall oil change at the end of the high driving season is probably best if you drive your Corvette year round.

I've never used Marvel Mystery Oil, so I have no opinion other than I never use any supplemental additives in any fluids in any of my cars. If you use the correct fluid, you don't need supplemental additives.

Chevron Techron is an excellent fuel additive for cleaning intake system and injector deposits, but it's only needed if the car develops some driveability problems that indicate injector or valve deposits.

There are also some additives that have a very high dose of detergent to free sticky rings or hydraulic lifters, but if you use CI-4 oil on a reasonable change frequency, this won't happen, and if a modern car develops the problem, a load of CI-4 oil for one interval will often free things up.

Duke

 

A good 10W30 or 10W40 oil is all you need in your car. The viscosity of both of these oils is 10 degrees above zero for safe starting in cold weather and the viscosity of a straight 30W or 40W depending on which one you use during the time the engine is operating. I use 10W30 in my 67' Coupe without any problems. I have been selling auto parts and oil for 27 years now and I don't believe in mixing different weights of oil. One should continue to use the same weight of oil in their engine. After plenty of mileage and a engine starting to use oil I then recommend going up to the next level, an example moving from a 10W30 up to a 10W40.

 

I am going to use api c1-4 in my 327 any special filter needed. I am using the old style canister. Thanks Mike

 

Here's the deal on oil filters - based on some SAE papers I have read. On a typical running engine the minimum bearing clearance is about 20 microns, so if you have a "10 micron filter" (90 percent of 10 micron particles are trapped in a single pass), it's not likely that particles 20 microns or more will reach the bearings. Particles less than 20 microns will typically pass through the bearings without creating any damage.

Over the years, filter media have improved, so I see no reason not to continue using the replaceable cartridge filter on vintage Corvettes since they use modern filter media that meet current OE and SAE requirements for automotive oil filters.

The research papers indicated that particle generation is primarily an engine break-in phenomenon. Once this is complete, very few particles are generated until the engine approaches end of life and the wear rate accelerates. This implies that changing the filter with every oil change may not be necessary, especially if the engine sees low mileage accumulation between oil changes. In the case of a vintage Corvette, you could just remove the cannister, empty it - to remove all the old oil - fill it with fresh oil (I do this because it takes less time for pressure to come up on startup because the pump does not have to fill the filter), and reinstall.

The above also implies that it would be a good idea to change the filter after the first few hundred miles on a new car, eventhough OEMs don't typically don't recommend this, but the factory fill oil is okay for the full recommended service inteval.

A couple of my cars have "upside down" filters, and in order to avoid spilling oil when they are removed I puncture the top of them which allows the oil to drain down. This precludes their reuse, so they have to be replaced, and given the cost and convenience of just installing a new spin on filter or cartridge I always change the filter as SOP - not necessarily because the filter needs replacement, but just of ensure that as much of the old oil as possible is removed.

Duke

 

Duke I wish you were my neighbor I would be hanging out at your house. ( you and my wife would both kill me). Thanks for the response. Mike