Group III vs Group IV - Cleaning Ability

[buster]

Link


Common question.

Quote:
However, from an academic point of view, I would expect the cleaning ability of a Group III and a PAO to be similar (generally poor). Again, academically, I would expect less risk of seal issues, etc., when switching from a Group III oil (as opposed to a Group I oil) to a PAO, as the Group III oil and PAO are chemically similar.

Ester synthetics have a higher degree of solvency than Group II, III or PAO base oils. This means they will dissolve additives and deposits more readily and may cause some seals to swell slightly. They also can remove some paints. These characteristics (other than paint removal) can be beneficial, so some oil formulators will add small amounts of ester base oils into their synthetic (Group III and PAO) formulations to improve these properties.

 

[Gabe]

The article states that it is almost impossible to know the basestock of an oil - and we hear this often.

If PAO has a lower pour point (-63 F) then couldn't we just simply test it?? I am thinking more of GC and RP which might have a higher percentage of PAO.

 

[buster]

All synthetic oils these days are using multiple synthetic base oils of varying quality in varying amounts. Synthetic meaning - Group III, III+, IV and V.

 

[bubbajoe_2112]

FWIW, when I pulled my valve covers to do a valve adjustment, my top end was extremely clean (J32A3, 106.5K miles). Mobil 1 5W20.

Same result on Mobil 1 for another J32A3 on ericthecarguy.com valve adjustment video.

 

[Capa]

An oil's ability to clean doesn't just reside in the base stock, and it is silly to view an oil and judge an oil simply according to its base stock when there are many other facets to an oil. Lets not forget when Sopus released their Ultra line (which ironically was primarily Group 3), they claimed that no oil cleaned better.