Originally Posted By: SteveSRT8
I've had a few lower mileage engines look that clean with no special oils. RP is a fine product, just a bit over-hyped as the second coming when many popular synthetics at much lower prices are usually available.
Note also there is no proof at all that that varnishing hurts anything, may be strictly a cosmetic benefit...
I pondered that condition for an evening or two.
Varnish is layer upon layer of hardened elements and it could be argued that it contributes/is part of the anti-wear package.
So then I pondered the cam in block engines of days gone by and compared them with today's high tech vvt systems and cylinder deactivation and I came to the conclusion that in older engines without the gadgets and gizmos are likely unaffected by that varnish layer and quite possibly protected by it to a certain extent.
But in today's engines varnish contributes to shrinking already small oil galleys and can cause the small hydraulic actuators that advance the cam for vvt and the hydraulically arrested valves to malfunction due to that hard build up.
These systems are labour intensive to access and repair/replace so an oil with a proven track record for deposit control is the only logical choice in engines with these feature b
Chev has made it easy with the dexos spec. It either meets it or doesn't,there isn't any meets or exceeds stuff going on.
Chrysler who needs a powerful detergent package for use in the hemi to stay on top of the hemi tick possibility makes an oil company jump through hoops just to get their approval when in all truth dodge should do as the Japanese have and formulate an oil for their specific weaknesses and strengths so the consumer can rest assured the oil was custom made for the conditions present in the hemi engine so the oil offers the best possible protection in the hemi's unique platform.
Like emissions. There must be significant blow-by at start up and the engines programming to get the engine up to operating temp as fast as possible which includes high idle,very lean mix,2 plugs which fire milliseconds apart to combust all the fuel present.
Based on what I know of these motors they need an oil with elevated tbn to combat blow-by gasses and fuel dilution and a ton of moly to reduce the co-efficient of friction making the rotating assembly easier to turn.
Zddp isn't really required at the stock level. The valve springs aren't pushing with enough pressure to necessitate requiring much.
Just spitballing
