Winter Oil

[DaveBr]

I am due to change oil on both trucks. I run Rotella 15W40. In the winter I have been running Rotella Synth 5W40 in the 93 with great results. Is it safe to run the synth in the 98 due to the oil spray nozzles for the pistons? I know it's a high volume pump but not sure about the viscosity.

Thought I'd ask for opinions before I spent the coin on the oil. Thanks.

[Hubert]

Fine in the oil sprayers its the same xw - 40 the 40 being key at warm operating conditions. Probably will help more in fact as the higher volume oil pump doesn't like to pump the cold thicker oil even more than the lower volume oil pump.