question about oil...

...ok, I have thought about posting this earlier but after reading Pauls response in regards to another question I had asked ( he described about only using the proper fluid that is called for) but thought I should post it as a new thread.

I believe in my '76 Cadillac with a 500 that I can use either 10w/30 or
10w/40. Well, before starting my engine the other week for the first time in a few years we had to add 5 quarts of oil as due to a leaking washer on the drain plug (now repaired) nearly all the engine oil had drained out over time. My brother had on hand 5 quarts of Quaker State 20w/50 and that is what we put in. HE insists that being that the car is older that 20w/50 is ALL I should use and that it will not hurt the engine and it will help with worn parts. My odometer reads about 54,000 miles on the car but not sure how many HOURS are on the engine.

What are thoughts about using 20w/50?? any big deal or not??

Dana.

20w40 is the most I would go with, on a low mileage eng.

This is an interesting question, since engine oil viscosity's are often misunderstood. A 10W-30 oil has the same viscosity throughout its temperature range, but it will protect the engine wear parts when cold like a 10 weight oil, and it will also protect the same parts like a 30 weight oil when hot. The base viscosity of 10W oil when cold is that of a 10 W oil no matter what. Given this information, the 20w-50 oil will give you the protection of a 20 W oil when cold. Hopefully you will follow this, because it gets tricky from this point. Assuming that the engine is at its half wear life (50K miles), and the ambient temperature is above 40 degrees, the 20W oil will protect the engine at the present time. If you were to keep that oil in the engine in the winter, it wouldn't give enough protection to the moving parts, since it is too thick for winter use.
Now, lets get to how they make a multi viscosity oil... It is all in the oil additive packages. That is why you need to change oil. The oil doesn't wear out, but the oils additive package is worn out. Don't change oil and the result is sludge in your engine. Ideally, I would use what the manufacturer originally recommended, but in a pinch, any oil is better than no oil.
Before someone jumps on the ZDDP bandwagon, this is a fancy term for zinc. Zinc was added to engine oil to protect the moving parts. In todays modern cars, the tolerances are much closer, and the need for zinc is lessened. Also, the Federal Government (i.e. EPA) is of the opinion that the emission systems (catalytic converter) will last longer if the use half the zinc in engine oils. When purchasing modern oils, pick up a bottle of any product that replaces the ZDDP. There are a number of them out there, and at present, I don't have any favorites. I used an additive for new engines that I got at the local Chevy dealer... that is, until GM pulled his franchise.

I have had much success in using the 20w/50 motor oil. I use it all of my vehicles except my Kaisers, I use 30w in them. If you're driving in hot climates, the little extra protection is a must. I only recommend, use a quality oil, some store brands and recycled oils are not what they should be and you will notice oil consumption when using them.

me I'm a fleet service type of guy. they make the fleet oil for use in large fleets with different types of engines. gas and desiel. we tested the oil when I worked the body shop in faith. up on the northern planes it gets cold. set a guart of 10-30 out there and a gt of 15-40. out side over nigh at 10 below. the 10-30 would not pour the 15-40 would. been using in ever since beside they are one of the few that still have zink in them. the 5-30s were a trick for .5 miles per gl better for the epa test. big thing is to service the engine requarley and on time.

I use this product, at the recomenndation of my mechanic, and my friends who own the antique fire apparatus that my car shares a space with. It's a little expensive, but hopefully doing my engine well. http://www.classiccarmotoroil.com/

Brendan Martin said:

I use this product, at the recomenndation of my mechanic, and my friends who own the antique fire apparatus that my car shares a space with. It's a little expensive, but hopefully doing my engine well. http://www.classiccarmotoroil.com/

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notice that it's the 15-40 fleet oil I mentioned. I don't think you can find a better lube out there. had a uncle who got 130 thousand mile a a El Camino using nothing but 10 weight pennzoil. he claimed that the bearings would only wair enough to let the oil flow. but then he changed his oil ever thousand miles on the dot. the car looked new when he traded it off to.

All good posts above. I can only share my history and current experience. A little known fact is that I'm also a big BMW fan. Since 1976, I've owned 5 of the exact same model BMW..... 1972 or 1973 Bavaria, the predecessor to the 5-series. I got turned on to these cars by an old boss while I was at Boston University. He had (and probably still has) a magnificent 1971 Bavaria, and he swore by Castrol. 10-30 in the winter, 20-50 in the summer. I adhered to this formula and it served me well, although recent learnings made me switch to 10-30 GTX all year long. I still have 3 of the Bavarias, which are turning into a long term project, to make one really nice one, and perhaps one decent one.

Moving on..... I recently had my '39 LaSalle engine totally rebuilt, and the old timer who did the work currently likes Shell Rotella-T, I think it's 15-40. It apparently still contains zinc. It's available in quarts and gallons, with the best price being for gallons at Sam's Club. I tend to hoard oil, based on price during sales. I joined the email program at Advance Auto Parts, and they frequently come out with e-coupons that sometimes make the Rotella-T even lower in price than at Sam's. So now, on all the older cars, I plan to use Rotella-T exclusively, and use up my Castrol GTX on the newer, family car and my Dakota pickup. Tom

the 15-40 Rotella is fleet oil. I'm glad most of us agree on this type of oil. you can also get it at all most all your quick lube places. if your not a change the oil your self kind of "person".

I've been running the Shell 15-40 Rotella T oil for a couple years now when I do my oil changes. In the 1990's when I helped keep up our high school's team buses and Dodge 15 passanger van we used Shell Rotella T oil in them. We had one bus with a 350 one with a 366 and two with 427 V-8's in them.

What about synthetic oil. I use that in all my cars, new and old. I add zinc to the older cars. I lost an engine before I started adding the zinc. A few dollars for the additive is cheaper than the $12,000 rebuild!