All, I suspect this post may generate as many different answers as those that reply ... :-)
I had an '03 Dodge Grand Caravan w/ the 3.3L. The manual called for two oils: 10W-30 and 5W-30. The 10W-30 was for use at temperatures above 0 F, whereas the 5W-30 (which is recommended) is for use at temperatures below
100 F; the overlap being between 0F and 100F.Being in MI, I could run either all year long, but I chose to use Mobil1
5W-30 synthetic oil, hoping to get better economy and cold-weather starting. At operating temperature, the van would develop minor tappet noise, and the dealership felt it was best to replace the lifters and change the oil (to regular 10W-30). When the oil change interval came due, I reverted back to synthetic 5W-30 ... and the tappet noise came back also.Now, I have an '05 w/ the 3.8L, which has the same oil recommendations. I'm planning to use 5W-30 at the next change interval, but let's assume the engine develops some tappet noise at operating temperatures:
With synthetic grades, has anyone ever mixed grades ... say 1:1 10W-30 and
5W-30? Any reason this should be a concern? I cannot understand why an engine (designed to run with either viscosity) would object. I also would not anticipate an adverse interaction between the oils. I would think that the resulting viscosity would be ideal.Thanks, Chris