I know this probably has been asked before, but I was wondering if anyone had any thoughts on what I was thinking about doing. I thought that I would use 1/2 Synthetic rotella 5-40 and 1/2 regular rotella 15-40. would this be benificial, yes/no? Thanks..

 

why are you doig this?

 

When I drove long-haul (early 1970's-early 1980's) this was a common thing...it was due to the incredibly high cost of synthetic when it was first available (and the need to maximize mpg's). In fact, one of the trucker magazines (Road King?) did a test of mixing synthetics with dino oil at different percentages and then running mpg tests. If I am not mistaken, the mpg effect was the same at 10% synthetic/90% dino as it was at 100% synthetic.

You might want to check out bobistheoilguy website...

 

as a mechanic i have used the rule of thumb that mixing unlike oils and coolant is not a good idea. different chemical makeups you have no way to know if they will react with each other until it has hurt your engine. but i have not heard of any proof that may happen but i am not willing to take the chance.

 

when the syn was comming out more there was a Dino/syn blend, wonder if that is still out...

 

there is. they usually call it a sythetic blend. the key with that is that is designed to run that way. also i haven't seen it with a diesel rating yet.

 

I've never liked the idea of mixing different types of oil. I've done it out of necessity with past cars, but I try not to. I've seen no proof of harm, I'm just concerned that the wrong mix might not be the right mix for my engine.

 

For only $35 extra the synthenic gives you get better fuel milage, the longer change interval, and a smother running engine. Spead the cost over the time it's well worth it.

 

you could mix the rotellas and be fine they will not be a issue. Both have the same add packs but dfferent basestocks. the 15w40 uses GP II/II+ the 5w40 uses GP III

 

Agreed. Still, I hated watching all that money flushed down the recycle tank at the local Auto Zone every oil change (these guys are so clueless, they don't even notice that I never buy anything there, but I bring in 5-gallon buckets of used oil regularly! )

Tomorrow I'm measuring for the length of hose I need and am ordering an oil bypass filter and 5-gallons of GP IV synthetic.

Far fewer oil changes, less wear, and (hopefully measurably) better fuel economy.