0W Mobil 1 - Engine oil - 986 Forum - The Community for Porsche Boxster & Cayman Owners

This a basic question .....but why have many gone away from the standard 0w40 that Porsche recomends? I am about to do a change

Supposedly some other aftermarket companies makes better oil than Mobil. Ask 10 different people what's the best oil and you get 10 different answers. There are never ending debates on this topic if you search it out.

From what I've gathered out of the millions of opinions on the subject, heavier oils like 5w40 and 10w40 are better for the IMS bearing. I switched to Syntec 5w40 last spring and noticed that the engine is quieter on startup. No more lifter? clatter for the initial .5 seconds of run time.

yeah .....lifter clatter is something i often note. if crank the engine before starting it tends not to be there

The last I checked the stock IMS rear bearing is not lubricated by engine oil.

It's not supposed to be, but the theory is that engine oil gets inside the IMS tube and washes away the "sealed" lubricant, thus leaving engine oil to lubricate the bearing (however, without sufficient flow to carry away deposits, hence why it is argued that more frequent changes are good). Modern Mobil 1 is not what it used to be. IMHO, there are better oils out there.

yes I thought it was sealed too...

The problem with 0W-40 Mobil 1 is the product’s inability to hold up under high temperature/high shear environments and “stay in grade” as demonstrated by used oil analysis. While the IMS from the factory is a sealed unit and its problems are not directly related to the oil’s performance (other than to the fact that the low viscosity of the 0W Mobil oil could hasten the oil intrusion into an already failing IMS bearing once the seals start to crap out), a lot of other engine components are directly affected by the product’s poor performance and limited ability to “go the distance”. In light of the fact that there are better oil selections available, the continued use of clearly inferior oil seems questionable……

Tired of red but I appreciate your input on this board.

My 2000 Boxster S owner's manual lists 10w40 synthetic and 15w40 conventional oils among the recommended types & viscosities. If it was OK then, why is it not OK now? Answer: 0w40 skews toward reduced fuel consumption. Since I am not focused on attaining the absolute minimum fuel consumption on my Boxster, it will most likely receive 10w40 syn on the next oil change...unless I go with 15w40 Swepco.

2 out of the 3 dealerships I've worked at used Mobil 1 0w-40. We're talking about thousands of oil changes a year just from one dealership. If there was a problem with that oil Porsche would remove it from the approved oil list and we would have seen more internal engine problems. The third dealership used Valvoline 0w-40 simply because it was cheaper than Mobil 1 and I believe Porsche approved it for use this year. In my opinion it's more important to keep the oil clean than debate which synthetic has the greatest protection.

Is this something that you check frequently?

We probably average 12-15 oil changes a day, six days a week, and have done so for more years than I’d care to admit. Along the way, we have regularly taken samples of oil for analysis; recording literally hundreds of results for several brands and many grades of oil; both synthetic and “dino”. What did we learn? Mobil 1 used to be a great oil; but it no longer is. Amongst the poorest performing grades under even minor exposure to heat or shear: 0W-40. Mobil’s 15W-50 continued to be a good performer, but that also changed about 3-4 years back, about the same time it lost all of ACEA ratings it once held. Now it is a shadow of what it once was, particularly in its performance in used oil analysis. Considering that the degradation of the Mobil 1 line did not happen over night, and has been the “topic of discussion de jour” on multiple web sites, I find it hard to believe that anyone remotely knowledgeable on the subject continues to believe it is a first rate product. Based upon what we have seen, we made a conscious decision to no longer use it in customer’s cars. Based upon our on-going data collection, that has proven to have been a wise choice……………..

SO what brand and weight of oil do you use instead of mobil 1?

Currently, we use Castrol Syntec 10W-40 (ACEA A3, B3, B4), which continues to demonstrate very good UoA's. We looked at their 5W-40, but found the 10W-40's ability to stay in grade and demonstrate better TBN's than the lighter version, particularly in M96's that are run hard. The Castrol Syntec line has continued to demonstrate consistent performance over several years. But as many oils "used to be good", we continue to evaluate the Castrol Syntec 10W-40 regularly in our "Trust; but verify" program. There are a lot of good oils out there, but you need to cut through the marketing hype and look at hard data to make an informed choice. If you want to understand more about oil parameters, take a look at the BITOG website; you will find more data than you ever wanted on all types of lubricants........

You can kill days of your life reading the BITOG site That said, there is an obscene amount of information to be had there.

We should all go back to the basics and do what we all normally do when we buy a new product. That is to read the owners manual and see what's recommended there. Chances are the oil recommended in the manual is what was used to develop the engine during R&D which I'm sure Porchse spent many hrs researching and $$ into developing this engine. I'm almost sure 0W-40 is not listed there. To date I have not found a reason as to why Porsche changed the oil used for older models and use 0W-40 as part of their fill. I seriously doubt there was much R&D done with 0W-40 to older models before this change. Only reason I can think of is to reduce stock and inventory........