What 15W-40 oil of yours has the highest zinc content? And what is that concentration amount specifically. I have a 67 Barracuda with a 440. The old timer that built the motor recommended T1 diesel 15W-40 due to 1300 zinc. However rumor has it you cut the zinc to 900. Can you advise?

Our Shell Rotella T1 30W or 40 would work well. Also, our Rotella T4 15W-40, T5 15W-40 and T6 15W-40. All of these motor oils have 1200 ppm of zinc which can be used for your 1967 Barracuda 440 flat tappet engine.

Zinc is an important component in Zinc dialkyldithiophosphate (ZDDP) which forms a sacrificial anti-wear film in an engine to help protect internal components such as a camshaft. Most Shell Rotella engine oils, including T6 5W-40 Full Synthetic Heavy Duty Diesel Engine Oil, contain approximately 1200 ppm of zinc which will benefit older and high-performance engines.

Is Rotella T4 safe to use in motorcycles? The back of the bottle says it meets or exceeds the specifications of JASO MA/MA2?

Yes. Shell Rotella T4 15W-40 Triple Protection Heavy Duty Diesel Engine Oil meets the JASO DH-2, MA, and MA2 specifications which are applicable for motorcycles with a wet clutch system. In addition, Shell Rotella^® T6 5W-40 and Shell Rotella T6 15W-40 Full Synthetic meet specifications. As always, please be sure to check your OEM and warranty requirements.