good plan! 
Oil Viscosity
Thread Starter
Intermediate
Joined: May 2010
Posts: 44
Likes: 0
From: Austin Texas
Oil Viscosity
Is 20w-50W oil to thick for a stock L48 in a Southern (i.e. Texas) climate?
This is not a ZDDP question, just a viscosity question. I have the oil, but am hesitant to use it until I get some feedback on way or the other.
Thanks!
This is not a ZDDP question, just a viscosity question. I have the oil, but am hesitant to use it until I get some feedback on way or the other.
Thanks!
Le Mans Master
Joined: Oct 2007
Posts: 7,451
Likes: 974
From: RI, Now Franklin/Nashville TN
20W-50 is specifically recommended in my 78 owners manual for temperatures down to 32 degrees! In a warm climate like in Texas it would be very suitable! I use a 15w-50 in my 78 stock L-82 and have for years in spring, fall, summer and very occasionally in the winter in The Northeast.
Acct suspended by request 19 April 2011
Joined: Jul 2009
Posts: 478
Likes: 0
From: La Porte In
Check the owners manual as Mike Ward says
Here at the forum the guys will run a wide range of opinions.
Depends on year engine and climate.
I have a 78 L82, live in Northwest Indiana. Car is stored 5 to 6 months. I run 10w30 according to the manual. I WON'T GET INTO ZDDP
Here at the forum the guys will run a wide range of opinions.
Depends on year engine and climate.
I have a 78 L82, live in Northwest Indiana. Car is stored 5 to 6 months. I run 10w30 according to the manual. I WON'T GET INTO ZDDP
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Acct suspended by request 19 April 2011
Joined: Jul 2009
Posts: 478
Likes: 0
From: La Porte In
Acct suspended by request 19 April 2011
Joined: Jul 2009
Posts: 478
Likes: 0
From: La Porte In
ZDDP
After that comment I decided to add the truth
Use conventional oil for ZDDP. That was what we had when these cars were built. Want best protection use Valvoline SynPower.
Period
This is according to independent studies backed by GM and Valvoline. Don't use Mobil 1 in an old engine. If engine is new use Mobil 1 if you like. Or if your owners manual calls for it. Better choice still Valvoline. The oldest oil in US History
After that comment I decided to add the truth
Use conventional oil for ZDDP. That was what we had when these cars were built. Want best protection use Valvoline SynPower.
Period
This is according to independent studies backed by GM and Valvoline. Don't use Mobil 1 in an old engine. If engine is new use Mobil 1 if you like. Or if your owners manual calls for it. Better choice still Valvoline. The oldest oil in US History
Last edited by 78 C3 Light Corvette Blue; Mar 23, 2011 at 10:38 PM.
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
ZDDP
After that comment I decided to add the truth
Use conventional oil for ZDDP. That was what we had when these cars were built. Want best protection use Valvoline SynPower.
Period
This is according to independent studies backed by GM and Valvoline. Don't use Mobil 1 in an old engine. If engine is new use Mobil 1 if you like. Or if your owners manual calls for it. Better choice still Valvoline. The oldest oil in US History
After that comment I decided to add the truth
Use conventional oil for ZDDP. That was what we had when these cars were built. Want best protection use Valvoline SynPower.
Period
This is according to independent studies backed by GM and Valvoline. Don't use Mobil 1 in an old engine. If engine is new use Mobil 1 if you like. Or if your owners manual calls for it. Better choice still Valvoline. The oldest oil in US History
20W-50 oil does not provide as good of cold start protection. By cold start I am not talking about it being cold outside. Check and see how long it takes for your oil pressure guage to jump up from 0 when starting after sitting for a few days. This time lapse is where 90% of engine wear occors. The longer this takes the more wear and that wear increases drastically as more time passes. Thicker oils take longer. The thicker oil also puts additional strain on the distributor/cam gears that drive the oil pump. They also reduce horsepower having to push the crank through thicker oil every RPM this causes additional loading on the main bearings and reduces fuel mileage. Why use them? Try the same time test with a good full synthetic 10W-40. The time it takes for the oil pressure guage to jump in a cold start will be less than half the time. That is way less than half the wear.
Le Mans Master
Joined: Oct 2000
Posts: 7,831
Likes: 5
From: Austin TX
Valvoline SynPower has under 800PPM zinc (ZDDP)
20W-50 oil does not provide as good of cold start protection. By cold start I am not talking about it being cold outside. Check and see how long it takes for your oil pressure guage to jump up from 0 when starting after sitting for a few days. This time lapse is where 90% of engine wear occors. The longer this takes the more wear and that wear increases drastically as more time passes. Thicker oils take longer. The thicker oil also puts additional strain on the distributor/cam gears that drive the oil pump. They also reduce horsepower having to push the crank through thicker oil every RPM this causes additional loading on the main bearings and reduces fuel mileage. Why use them? Try the same time test with a good full synthetic 10W-40. The time it takes for the oil pressure guage to jump in a cold start will be less than half the time. That is way less than half the wear.
20W-50 oil does not provide as good of cold start protection. By cold start I am not talking about it being cold outside. Check and see how long it takes for your oil pressure guage to jump up from 0 when starting after sitting for a few days. This time lapse is where 90% of engine wear occors. The longer this takes the more wear and that wear increases drastically as more time passes. Thicker oils take longer. The thicker oil also puts additional strain on the distributor/cam gears that drive the oil pump. They also reduce horsepower having to push the crank through thicker oil every RPM this causes additional loading on the main bearings and reduces fuel mileage. Why use them? Try the same time test with a good full synthetic 10W-40. The time it takes for the oil pressure guage to jump in a cold start will be less than half the time. That is way less than half the wear.
Also, I am shocked that a test paid for by Valvoline determined Valvoline is the best oil.
Acct suspended by request 19 April 2011
Joined: Jul 2009
Posts: 478
Likes: 0
From: La Porte In
Last edited by 78 C3 Light Corvette Blue; Mar 24, 2011 at 12:58 AM.
