no offense rmm, but oil analysis results prove that your comment that 'dino oil is just as good as synthetic when changed at lower intervals' is just nonsense. The protective additive packages are better in chemistry, better soot suspension(cg-4,ch-4,ci-4), among other benefits. Your one car/case experiment is hardly conclusive evidence that synthetic causes leaks. You may have had this happen coincidentally, or not. However there are several members with 200K plus on older MB diesels, and have switched to synthetic with no extra leaking. Rmm, the thread was regarding a diesel E300. Dino is NOT recommended, a CG-4 synthetic is required, as a minimum.

In addition to this, I have two friends who currently each bought '97 E300's with around 100-120k on them, and have since switched to delvac 1, with no problems. I run delvac 1 in my E300, and its amazing how much better it runs than on the garbage syntec or mobil 1 the uneducated mb dealer put in the car. My iron and other wear metal levels in my oil analyses dropped significantly after two runs of delvac. The first run was amazing at how much the TBN was depleted, as it was working hard to clean out the crap the syntec left over.
Delvac 1 or amsoil series 3000 are true group 4 synthetics, the lower priced formulations of amsoil, as well as rotella t synthetic, valvoline premium blue, and other popular diesel oils, are group 3 quality basestocks, and are not considered quite as premium. Txbill will have comments to argue, but my point is that delvac1 and amsoil are the utmost top quality. Good/average results can be had with lower quality group 3's. Why put anything in but the best? You can go 10k on delvac with better protection than 5 k on rmm's dino.

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2004 Ram 2500 Cummins HO
2000 Jetta TDI
1999 E300 (sold)