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Anyway so the consensus is, no conventional oil can handle fuel dilution well? I just wanted to get an answer thats all …
Well … no motor oil is probably going to handle fuel dilution "well". But if you are going to be doing relatively shorter oil changes (3-5K miles) I wouldn't rule out conventional oils -- even in a turbo equipped engine. The thermal/oxidative stability of GII's is far above what the old conventional GI's were years ago, so I don't have great concerns here about modern conventionals not being able to handle the heat in a turbocharger equipped engine at reasonable OCI's.
In the article (at Chevron's site)
The Evolution of Base Oil Technology, Kramer makes the following statement in the second to last paragraph …
" … Turbine oils made from hydroisomerized Group II base oils and the appropriate additives have demonstrated significantly longer TOST lives than turbine oils made with Group I base oils. In fact, they commonly outperform the traditional “synthetics” made with PAO. …"
Agip even advertises their Group II's as performing like synthetics …
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Agip uses Group II base oils for its non-synthetic. … … Agip’s non-synthetics offer performance equivalent to most synthetics on the market.
Most conventional SM rated oils don't get a premium add-pac (or probably as good add-pac as synthetics) so they're not really formulated for very long drains. They're more of a low cost solution to meeting the latest SM specification -- and they're not as shear stable as synthetics. Likely the best conventional Group II motor oils are to be found among the HDEOs. I would consider a 10w30 HDEO with perhaps 1 quart of 15w40 mixed in to raise the HTHS and viscosity a little. Or, even a straight 15w40 HDEO which would give up a little fuel economy compared to a 10W30, but would provide more viscosity protection if you think fuel dilution will really be an issue. If you are going to be doing shorter 3-5k mile oil changes, I don't see synthetics as offering much advantage to these options -- particularly the 15w40.