Jay, I take it as a given that most participants on this forum know the general nature of the two primary synthetic compounds. But that’s not a fair assumption.
I was really hoping someone else with a formal chemistry degree would add a helpful sentence or two, but I guess I’ll take a stab at picking apart Mobil’s "helpful" answer:
1) The seal issue is bogus. If you run a 100% PAO formula your seals will harden and your engine will leak oil. It’s just a matter of time. The reputation that synthetic oils
cause leaks (especially in older cars) is due to this effect ... and it is mostly Mobil’s fault. It is true that esters have the opposite effect in that they tend to swell seals. But, I’ve yet to even
hear of any seal trouble with Red Line’s polyol ester formulas ruining seals. Most synthetics (even Mobil 1) use
both compounds in their formula and this is not mentioned anywhere in their answer. As for compatibility, esters are added to PAO to make it
more compatible (miscible) with other compounds and additives. Verdict: Mobil’s answer is
seriously misleading.
2) In terms of temperature, I believe that esters offer similar low-temp performance when compared to PAO, maybe even slightly superior. At the other end of the scale, it is no contest. Esters rule the high temp end of the temperature scale surpassing PAO’s ability to lubricate by a 100 degrees Fahrenheit or more. I’ve seen tests which show that PAOs tend to form hard deposits when pushed passed their high-temp limits. And at these temperatures (say, in a turbocarger) esters are still doing their job with little problem. This is why esters can be used in jet turbines while PAOs can’t. Verdict: Mobil’s comments are one sided and imply that esters do not compare favorably with PAO across a full temperature range (again,
highly misleading).
3) Water and moisture. OK, PAO has an advantage here ... but unless we’re talking about looney-tunes length drain intervals or a car with serious moisture contamination problems, the esters tendency to attract moisture is not a problem. I’ve run Red Line for 7,200 miles and have not had a problem with oxidation or moisture contamination. My results were even skewed because of a coolant leak.
![[Roll Eyes]](images/icons/rolleyes.gif)
So, if you want to choose an oil to
store your car in a garage, perhaps Mobil 1 is for you. If you want to drive it ... hard! Then a formula like Red Line will protect your engine better.
![[Big Grin]](images/icons/grin.gif)
4) As for anti-rusting capabilities, see #3 above. PAOs advantages here are merely theoretical. Look at the results in the Used Oil Analysis section. Look at the Red Line samples and look at the iron levels. If corrosion was a problem, you’d see elevated iron levels and I don’t think I’ve seen one example of this. Again, Mobil making statements the way they did suggests there is a problem with esters ... when there obviously isn’t.
![[Roll Eyes]](images/icons/rolleyes.gif)
A year ago I got in an argument with an Amsoil diehard about esters vs. PAO and he pointed me towards a chart which assigned values between 1 and 5 showing the strengths and weaknesses of PAOs and esters. The chart and accompanying article were biased heavily towards PAO. The problem was they weighed all the attributes equally. Compatibility with a painted surfaces was weighed as heavily as high temperature stability!
![[Roll Eyes]](images/icons/rolleyes.gif)
Mobil doesn’t go this far … but there answer was in the same, smarmy vein.
It’s kind of like Castrol touting the benefits of Group III stocks being sold as synthetic oil. One of the important advantages was reduced cost ... but notice they didn’t reduce the retail price at all.
![[Roll Eyes]](images/icons/rolleyes.gif)
That kind of smarmy, crooked politician double-speak really irks me and this is the reason Mobil’s one-sided, misleading answer rubs me the wrong way.
’Kule and some others can point out where I’ve gone astray. I’m not a chemist but I’ve been looking at the lube issue for several years now. There may be other attributes to esters I’ve overlooked (such as their polar nature and affinity for metal surfaces) which others may want to comment on.
L8274, you are correct ... but we all pretty much agree here that any decent oil will do for gently/modestly driven vehicles. Even PAO or Group III are overkill. That really isn’t the point here at all, we are talking about superlatives.
---
Bror Jace