Which Would You Use??

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Mar 15, 2003
I have two VW Diesels (listed in sig). I have been running Mobil 1 Formula M 5W-40 low SAPS oil in the '09 for the last 82,000 miles. Being in Houston, I figure the slightly higher HTHS can't hurt, and all other critical parameters (really, mostly just the SA) are equivalent to the ESP 5W-30 507 rated Mobil oil. The Touareg TDI is new and will be on the Castrol 507 dealer oil until about 40k miles...maybe (it is free after all). The questions I am wrestling with are: 1. Do I wait until 40k to switch the Touareg over to the FM 5W-40, or do I switch it over asap? 2. Do I switch both diesels over to Amsoil AEL Euro Car formula? I know I am splitting hairs and making an issue out of nothing. I could run any of these oils forever and probably never tell the difference. But what the heck....it's oil! What else are we going to talk about?? smile
The allowed sulfated ash percentage is lower on VW507 than on MB229.51. VW507 allows .6% and MB229.51 allows .8%. That is the difference between ESP 5w30 and ESP Formula M 5w40. I would wait until warranty is up before switching the Touareg to ESP Formula M. VW will be quick to deny warranty on the aftertreatment system if you haven't used an oil meeting VW507.
Mobil lists FM at .6% SA, same as the ESP 5W-30. It could go higher though per the MB spec....but for now it is .6%. I watch their literature! My DPF ash load at 120,000 miles is the same as virtually every other tested car at Fred's TDIClub (on a per mile basis). Most of the guys there are running strictly 507 oil.
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Personally I don't see what you're gaining on the 40w vs the 30w. The HTHS is just a smidgen higher with the 40w. I would not be surprised if the formula M met 507.00 (40w oils are not part of the 507 spec). I lived in Houston and with the traffic and climate I would stick with the 30w.
If I lived up north where it was commonly below 40F, or if I was a short-tripper, I would lean toward the 5W-30. Being in a hot climate and running mostly longer trips has me wanting the higher viscosity.
Actually, just for interest, MB allows use of 228.51 in its' DPF equipped passenger car diesels: 1.0% ash. I'm using Delvac 1 LE 5W30 in an 09 BMW X5 35d, because of rapid, excessive TBN depletion and high wear numbers (acidic corrosion??) with the dealer supplied Castrol SLX Professional OE 5W30 (12.6 vs. 6.4). I've noticed in one standard OCI (9-10K mi) the Castrol burned ~1 qt whereas the Delvac has burned virtually nothing in 11K mi. So even though it has more ash (1.0% VS 0.6%) the Delvac may be putting less ash in the DPF. Charlie
Thats an interesting point about the actual ash going into the DPF and I've been wondering about it myself: If an engine uses no noticeable oil during an OCI, could one not use a normal SAPS oil? How will the DPF fair better in an oil-consuming engine that uses a low-SAPS oil?
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