In a follow on to Doc's #60 post above about viscosity, for those reading this that might not know what the viscosity numbers mean that he got from his lab tests, here is a chart that you look them up on:
http://www.bobistheoilguy.com/viscosity-charts/
The chart shows that oil viscosity tested in the 8 to 9.5 range is a low to high 20W.
I've been testing nearly every oil change on my previous '11 RT and now on the '14 RT and they both test out about the same depending on the oil used. My tests show that most good synthetic oils hold up very well from 3-4000K miles, at that point being in the 30W range.
I've decided that from now on, I'm going to set my change level at 4500 to 5000 miles with filters every other time.
I don't contest what BRP Steve says about running oil to 9300miles but I'm just not comfortable with that, knowing that the oil will be down in the low range of 20W or so. However, most all new cars are now running a 0W-20, and some are going to even thinner oil in the near future. The question is, can the 1330 motor last for thousands of miles running on thin oil? Maybe BRP knows and perhaps that was implied by BRP Steve saying it was safe to run the long miles. I don't know that and will do two changes instead of one. I do my own so the cost is not an issue for me.
Not touting any one oil as I don't know yet how Mobil 1 will test out for me, but Amsoil and Valvoline has tested very well. Valvoline is now $8.69 at Walmart in my area with Mobil1 just under $10.
Pretty hard to beat BajaRons package deals for Amsoil. I get it at a discount and can't beat his prices. I suspect he snitches it off the loading dock somewhere! LOL...kidding Ron.
BTW, I'm running Mobil 1 for the first time with nearly 5K on it now and will be testing it shortly. Willl report here what I find.
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