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I have seen some comments that it is not good to use Mobil 1 synthetic in a new engine , but once the engine is broken in, Mobil 1 is fine to use and actually a good choice.

Does anyone know what the reasoning is here?

Also, can anyone explain the problem that some have mentioned with switching back and forth between brands of oil?
 

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I think hte concern with older engines switching to synthetics is that the synthetic supposedly cleans better, so it breaks down the "sludge seals" formed by dino oil, which results in oil leaks.

mobil's site has lotsa good info
here's their myths page
http://www.mobil1.com/why/myths.jsp

oh, I switched to mobil 1 on my 2.5l at 95K miles and had no problems with oil leaks up til 116K when it blew
 

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There are several things going on here. Older engines didn't have microfinished cylinder bores and the closer-to-final tolerances that older engines had, so it used to be recommended that synthetics not be used during break-in so that the minor wear that needs to happen to have the rings hone to the cylinder bores properly and the bearings to bed-in properly, etc. will happen.

Now that these internals are set really closely these days, its generally not as necessary for this break-in process to occur. So cars these days have shorter, or in many cases NO break-in periods.

Lots of higher-perofrmance cars (Vette/Porsche/AMG (Mobil1) BMW, etc.) are filled with synthetics at the factory that aren't required to be changed till the first scheduled maintenance (7000-20000 miles).

As for mixing, there are some known problems when mixing the two different main types of synthetics (PolyAlphaOlefins vs esters).

I believe, though, that the last two Mobil1 formulas (TrySyn and the new SuperSyn) actually have both types in it.
 

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I've been told by a few BMW techs the the BMW High Performance oil (which is supposedly sythetic) made by Castrol is crap :thumbdwn: and they don't even use it in their own BMWs. I was also told not to switch, pick one oil and stick with it. No switching back and forth.
 

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Sean said:
I've been told by a few BMW techs the the BMW High Performance oil (which is sythetic) made by Castrol is crap :thumbdwn:
I bought some BMW sythetic off a friend and used it in the 3.2 when I swapped it in. I noticed the engine oil runs much hotter than with the old engine. Im hoping its just the oil. Switching back to Mobil 1 after the next oil change
 

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M Mad
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JJKK said:
I have seen some comments that it is not good to use Mobil 1 synthetic in a new engine , but once the engine is broken in, Mobil 1 is fine to use and actually a good choice.

Does anyone know what the reasoning is here?

Also, can anyone explain the problem that some have mentioned with switching back and forth between brands of oil?
Old wives tales never go away.

In the early days of synthetics, some of them had excessive cleaning properties and caused some trouble with older engines that had a lot of sludge buildup. Both from causing leaks, to loosening up so much sludge it clogged the oil passages. This had not been a problem since the 60s.

About switching brands, in the VERY old days the two main types of crudes (Pennsylvania and California) were different enough that they could cause trouble if mixed. So you didn't want to switch oil brands in case you mixed crude base stocks. With modern refining, all the oil is pretty much the same once it comes out of the refinery. This has not been a problem since the 50s.

Of course the oil companies would like to not switch brands, but that is because they want your money.

As to what oil to use in your BMW, if it is under warranty, you should use BMW oil. The reason is, since BMWs come with a maintenance agreement, where they supply things like the oil, if you use other than the factory recommended stuff, they COULD (not that they will, or even that it is likely) void your warranty if any problems occured that might be related to supplied parts (oil). And as I understand the Magnuson- Moss Warranty Act, since they suply the il, they do not have to prove that the other oil caused the problem, just that you used other than what they supply. For other (items not supplied under maintenance agreement), they would have to show that the aftermarket item actually caused the problem.

As to BMW Synthetic not being the same as off the shelf Castrol (or Valvoline, I have heard both as sources depending on the timeframe), this is most likely true.

BMW specifies ACEA A3/B3 spec oil. ACEA is a testing standard like SAE. No off the shelf -30 weight oil meets ACEA A3/B3. They only meet ACEA A1/B1. I have checked every -30 (0W-30, 5W-30, 10W-30) I could find and if they are ACEA tested, they only meet A1/B1

So if BMW oil actually meets their own specs, it is not the same as off the shelf anything. I will check today when they do the annual oil change on the Roadster.

BTW for the Redline fans, Redline is NOT ACEA tested. I have seen posted that when questioned, Redline said they figure their oils would meet ACEA A2/B2. Not quite up to BMW specs. This does not mean I don't like or dislike Redline, just pointing out something you should know.
 

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M Mad
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Sean said:
I've been told by a few BMW techs the the BMW High Performance oil (which is supposedly sythetic) made by Castrol is crap :thumbdwn: and they don't even use it in their own BMWs. I was also told not to switch, pick one oil and stick with it. No switching back and forth.
There is a lot of misinformation out about Castrol oils and oils in general.

So I checked with a friend in teh petroleum business.

1) "Castrol buys overstock from other companies since they have no refinery themselves" - Actually a lot of companies buy base stock lubricating oils from other companies. Even those who have refineries and produce their own base stocks. I forget which one buys and sells, but Chevon and Texaco do this.

Nobody has "overstocks" of oil base stocks. What happens is companies that buy base stocks contract with the refineries to "make" exactly the base stock they want.

2) "Castrol isn't real synthetic, it is made from dino oil" - There are two ways of making a synthetic oil. First, a synthetic oil is one that is optimized for lubrcating properties. In normal oil there are some very good lubricating molecules and some not as great molecules. With a synthethic you make as much of the base stock good molecules as you can.

The two ways of doing this are to build up the molecules from smaller molecule (synthesizing) or specfically cracking (breaking) larger molecules into the proper size. Both produce the same end compounds, so it doesn't matter how you get there.

Also in conversations with my friend, he stated that with modern cracking techniques it is possible to make a BETTER lubricating oil from the cracking process than from the synthesis process. So Castrol COULD be a better oil since it is not built up from smaller molecules.

Also ALL lubricating oils come from dino oil. The question is whether you take the smaller stuff and build good stuff, or take the big stuff and cut it to size to be good stuff.

BTW the first way to make synthetics was via putting together smaler molecules, the cracking came with later technology.
 

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Parump said:
Costco is now selling Mobil synthetic oil - 5 - 30 wt for approximately $4.00 per quart - six per box. Previously, they only sold the synthetic 0 - 30 wt type.
I just saw this today. $21.99 for 6 here. Its the cheapest I've seen available at any time, without waiting for WalMart to have 5qt jugs for ~$16 or looking for Targets that have it for $3.19.
 
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