new member has oil question

[Turbo]

I have a 3.8 turbocharged flat tappet pushrod motor. After reading many posts I have narrowed my oil selection down to two Rotella T-Synthetic 5w40 or Castrol Syntec 0w30. Can someone please help me decide with some opinions. I am leaning toward the Rotella but still undecided. Thanks for the help.
Sal

 

[Edmond]

What was the factory fill?

 

[simple_gifts]

What car? SFI Buick?

 

[Steve S]

40 in summer and 30 in winter.

 

[Dr_No]

^^

Go with steve

 

[daman]

Definitely go with a synthetic to help with the heat, you also could pick your favorite oil and add SLOB or VALVOLINE SynPower OIL TREATMENT to boost zink and phos witch is important for flat tappet engines..

 

[GMBoy]

I'm guessing this is a 3.8SFI turbo Buick I've got a a mint 87 Grand National that has had a diet of Mobil 1 until 40,000 miles and then went Redline. Now has 61,000 miles. I can only say that I'd rather have a syn oil in my turbo, but have never thought about Rotella T. Hopefully somebody with more knowledge with oil issues and flat tappets will chime in.

 

[daman]

Turbo's run HOT, i would stick with a good synthetic,10w30
or 40..