That is an interesting pdf.

But it still leaves me with no idea about what type of oils we should use on older cars. For newer ones, no doubt we should follow MB's current recommendations.

It seems that reduced additives like ZDDP in newer oils (to protect catalysts) might be detrimental for older cars. The report says that base IV oils are not good at dissolving additives, but I presume they have a way to do it. Looks like Syntec (Now Edge) may have moved to base III+ to improve performance in older cars, but Castrol don't divulge much about additives. Mobil do, for example in this chart:
http://www.mobiloil.com/USA-English/MotorOil/Files/Mobil_1_Product_Guide.pdf
(unfortunately doesn't include Delvac, but this is what Mobil says:
Considering age of our old diesels, I can't get too excited about specific oil. But I do use Mobil 1 - 15W50 or TDT in our W123 300D. And in my old SL summer car, I have recently used High mileage 10W40.

__________________
Graham
85 300D,72 350SL, 98 E320, Outback 2.5

Can you please share with us where you obtained this information?

__________________
1987 300TD 309, xxx 2.8.2014 10,000 mile OCI


Be careful of the toes you step on today, as they may be connected to the ass you have to kiss tomorrow. anonymous

“Be who you are and say what you feel, because those who mind don’t matter, and those who matter won’t mind.” Dr. Seuss

The fact that they are not identical oils is obvious from the fact that the information on the two data sheets is not identical. Identical oils would have identical data in all respects.

As to the base stock info, in part it's based on gsxr's comments, in part it's based on the information on the avlube site.

__________________
14 E250 Bluetec "Sinclair", Palladium Silver on Black, 153k miles
06 E320 CDI "Rutherford", Black on Tan, 171k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver, 142k mi, wastegate conversion

19 Honda CR-V EX 61k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

HOWEVER, I just talked to someone at AV Lube, and her contention is that anything labeled Mobil 1 is Group IV, whereas the Mobil Sypersyn is Group III.

__________________
14 E250 Bluetec "Sinclair", Palladium Silver on Black, 153k miles
06 E320 CDI "Rutherford", Black on Tan, 171k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver, 142k mi, wastegate conversion

19 Honda CR-V EX 61k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

I would love to see something from Mobil Exxon confirming her "contention". Or have someone from the company tell you that. Until then I'm going to be using Red Line as they use a Group V stock for both their 5w/40 and 15/w40. The TBN for both oils is 9.5. I talked to Dave in technical support at Red Line this morning.

I have used Amsoil in the past, but I'm sick of their Ponzi scheme sales program.

__________________
1987 300TD 309, xxx 2.8.2014 10,000 mile OCI


Be careful of the toes you step on today, as they may be connected to the ass you have to kiss tomorrow. anonymous

“Be who you are and say what you feel, because those who mind don’t matter, and those who matter won’t mind.” Dr. Seuss

Since you wrote, I just got an email from a tech at Predictive Maintenance Services (the oil analysis side of avlube)...I would trust him more than the woman in sales I spoke to. He confirms that M1 TDT is Group III, Delvac 1 is Group IV. His note in part reads: "... really the advantage for GP4 oils are in the viscometrics as they flow better at severe cold temps and retain their viscosity film at extreme temps. On both the products the additives are similar so for detergency, dispercency(soot control), anti-wear, etc the performance is similar and not too much more to be gained by the Delvac1. Soot thickening is always a concern as it will make the Visc heavy and hinder cold starting flow, but the major concern is abrasiveness of soot carbon and that is best managed by the best glass media filters available for your engine."

__________________
14 E250 Bluetec "Sinclair", Palladium Silver on Black, 153k miles
06 E320 CDI "Rutherford", Black on Tan, 171k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver, 142k mi, wastegate conversion

19 Honda CR-V EX 61k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

http://www.mobiloil.com/USA-English/MotorOil/Car_Care/AskMobil/Diesel_Motor_Oil_Differences.aspx