Maybe the CU wear (151 ppm) on the two year 5k OCI < CU wear (188 ppm) on the one year 5 k OCI ,
because as the engine wears from usage, the bearing wear rate decreases.
The high CU concentration could be a result of using a Polyolester(POE) type base oil.
Understand this type of oil is highly hydroscopic and aborbs water from atmospheric water vapor.
When this POE absorbs water the oil becomes acidic. This acid is a different type of acid that is created from combustion products
and is neutralized by the calcium additive, bottle of TUMS anti acid tablets.
The POE acid would corrode the CU sleeve bearings.
The GF-5 spec has a sequence V111 test for measuring the corrosion rate on copper based bearings.
A small .7L single cylinder engine is run for 40 hours at 3150 rpm with143C oil temperature.
The bearing can not loose over 26 mg of CU weight to pass the test.
The uncertified GF-5 RL motor oil maybe not pass the sequence V111, ASTM D6709 corrosion test.
RL could be using some type of additive to reduce the hydroscopic affects of the POE base.
If not, the engine would have to be run to bring the oil over boiling temperature on a regular basis to help evaporate off the water.
The POE oil used in gas turbines do not have copper sleeve bearings.
The POE oil used in refrigeration compressors do not have copper bearings.
Would rather go with a POA oil for automotive application for about the same price, since $ Amsoil SS ~$ RL
Understand the polar properties of POE helps seal up the leaky lifters and is a trade off between copper bearing corrosion and a pounded up camshaft.
Sending off a 4k OCI sample of 5w20 PP today to Blackrock.
Great points on paper, we think alike my friend. The fallacy to your argument is assuming you know the Redline time tested formula that has been formulated to minimize the negative effects of esters, I would now admit the base is not a majority esters. Then you have to ask what percentage of esters would you get all of the benefits without the risk, and that is their formulation my friend. Look at other UOA's. Also look at tech specs and testing, Redline does test off the charts in many areas, thus proving there is something different and desirable in that oil. And that oil was in my truck for two years, with zero water problem. So looking forward to your response, this is the type of conversation that leads to real answers. Challenge everything.
PAO has negative possibilities as well, just a thought Syn may disagree. But Amsoil has no regulations regarding how much PAO they have to put in their formula to call it synthetic, but the euro oils maybe do, they certainly used to have these regulations. Gives Amsoil an upper hand to mix their oils to minimize PAO negative effects. Here is one conversation at Bobs,
PAO versus Ester.
Laymen breakdown of PAO versus Ester from LubesNGreases mag. Oct. 2010 Pg.44-45
Ability to withstand heat/oxidation.
PAO:Good
Ester:Good-Excellent
Hydrolytic stability. ie.water absorbs into the oil.
PAO:Excellent
Ester
oor
Additive solubility.
PAOoor
Ester Excellent
Seal Swell.
PAO: Poor
Ester: Excellent
Vis.
PAO: Excellent
Ester:Excellent
Film Strength,
PAO: Good
Ester: Good
This is why Burla chose Esters over PAO, neither if perfect, but between the two I would opt for Ester. Look at the "poor" rating on esters and it is Hydrolytic stability (water), but look at my 2 year oci, no issue there. Water content 0.0 both UOA's.
