Oil Film & GM's Spun Beariings: What Went Wrong?

[A_Harman]

Originally Posted By: Ram01
I thought GM did extensive real world testing on these motors


They did, but they only build test fleet engines to the limits of the designed tolerances. Apparently these engine were assembled outside the allowable tolerance limits.

 

[A_Harman]

Originally Posted By: OneEyeJack
After all this discussion it comes down to quality control, nothing mysterious, just mistakes.

Years ago in amateur racing I had a oil pressure drop half way thru a race, from 60 to 40 psi. On tear down a rod bearing spun. sheared off the tabs. Now both sides of the bearing became the lubricated bearing surface. I left it alone and raced the rest of the season like that and it worked fine. I called is "double full floating bearing". It was a 1300cc Alfa in E/P.


Was the "double full floating bearing" noisy?

 

[demarpaint]

Originally Posted By: aquariuscsm
Originally Posted By: Zaedock
[Another cool BuickGN factoid was that of all the oils he tried (syn and conventional) the only oil that would keep his 650HP 3.8L engine together was 20W50.


^^This. Plus he told me in a pm that upon engine tear downs,conventional oils showed less wear than synths. He also said that thicker oils (20W50 for example) protected the bottom ends better than thin oils. BuickGN knew his stuff!


He did know his stuff. He also shed a lot of light on the value of a UOA for determining engine health. LOL

 

[SteveSRT8]

Originally Posted By: demarpaint
Originally Posted By: aquariuscsm
Originally Posted By: Zaedock
[Another cool BuickGN factoid was that of all the oils he tried (syn and conventional) the only oil that would keep his 650HP 3.8L engine together was 20W50.


^^This. Plus he told me in a pm that upon engine tear downs,conventional oils showed less wear than synths. He also said that thicker oils (20W50 for example) protected the bottom ends better than thin oils. BuickGN knew his stuff!


He did know his stuff. He also shed a lot of light on the value of a UOA for determining engine health. LOL



Hahaha, how true. We all get excited here about UOA's and many times you'd have been far better off not spending the money...

 

[Trav]

Originally Posted By: SteveSRT8
Originally Posted By: demarpaint
Originally Posted By: aquariuscsm
Originally Posted By: Zaedock
[Another cool BuickGN factoid was that of all the oils he tried (syn and conventional) the only oil that would keep his 650HP 3.8L engine together was 20W50.


^^This. Plus he told me in a pm that upon engine tear downs,conventional oils showed less wear than synths. He also said that thicker oils (20W50 for example) protected the bottom ends better than thin oils. BuickGN knew his stuff!


He did know his stuff. He also shed a lot of light on the value of a UOA for determining engine health. LOL



Hahaha, how true. We all get excited here about UOA's and many times you'd have been far better off not spending the money...


+1 Unless the engine has known issues or something is suspect like unexplained coolant loss or fuel dilution, might as well open the window and throw the money out.
Spend the $25 ($35 with TBN) + post on better oil and filter, more bang for the buck in the long run IMO.

 

[KrisZ]

Originally Posted By: Trav


+1 Unless the engine has known issues or something is suspect like unexplained coolant loss or fuel dilution, might as well open the window and throw the money out.
Spend the $25 ($35 with TBN) + post on better oil and filter, more bang for the buck in the long run IMO.



Yeah, but then you can't post your result on the interwebs and be perceived as an oil guru since not only you know what UOA stands for, but you've done one or a handful. Then of course you can start interpreting other peoples UOAs to further solidify you oil guru status

 

[Rosetta]

UOAs are for airplanes, not cars ... a Lycoming/Continental/P&W engine overhaul is expensive? Yeas, but aircraft owners do for safety sake, to know how the engine is doing, if it is still secure to fly. For a car, is Waste of money. If the engine is wearing, I wouldn't tear it down early,just for knowing the future. No car will fall down of the skies. I can park the car go to rest area and call a Tow job.
My 2 bucks.

 

[Ram01]

Will going to a heavier motor oil weight help ????