Re: oil, gas options?
You mean there is no pressure relief valve ? Used to be a concern with very high oil pressure that the bearings would erode, that may be passé.
Back in the day the rule for race engines was 10 psi/1000 rpm hot.
Once upon a time there was a mfr that specified synthetic oil in order to meet a EPA MPG goal. A second reason was for extended change intervals. Neither had a technical reason.
My point is that without knowing the design requirements that called for synthetic, we are just guessing as to the need.
OTOH I understand the reason for a 91 octane requirement. IMNSHO it results from poor design decisions (anyone notice that the current Hemi has the same issues - one exhaust valve and dual plugs) but can understand it.
The oil requirement OTGH & 8 quarts instead of 5 is less clear unless there is an expected condition in which oil starvation may occur. Both could address that.
The Mercedes specs indicate that the reason is for extended oil change intervals, use of the FSS, and a 1% fuel savings, and not that there is anything wrong with dino oils:
"MB sheet 229.3 approved oils
for passenger cars with gas and diesel engines with extended drain interval indicator FSS up to 20,000 km, or 40,000 km - 25,000 mi, current minimum spec for 1998+ MB engines, min. 1.0% fuel saving compared to 229.1, based on ACEA A3 B4.
MB sheet 229.5 approved oils; "MB Longlife Service Oils"
for passenger cars with gas and diesel engines with extended drain intervals beyond 229.3 oils, to 30,000 km, min 1.8% fuel saving, first oils introduced summer 2002. ACEA A3 B4. For gas engines of the M100 series, gas engines of the M200 series and diesel engines of the OM600 series (not models with Euro 4 diesel particle filters).
229.5 engine oils must be used with fleece oil filter designed for use with 229.5 engine oils."
See engine oil difference between 229.3 and 229.5 - Mercedes-Benz Forum for more than you ever wanted to know.
Last edited by Padgett; Apr 1, 2014 at 11:34 AM.