Castrol Syntec (5W-40) - 986 Forum - The Community for Porsche Boxster & Cayman Owners

I recently changed my oil from Mobil 1 "factory fill" 0W-40 to Castrol Syntec 5W-40 after Advanced Auto had a special promotion of 5 quarts for $25 and a free K&N oil filter. I picked up 20 quarts to save some dough. I decided against Royal Purple at the last minute due to price and availability. A local Mobil 1 oil change shop (actually no longer owned by Mobil 1 but everything else is the same) agreed to do the change for $30 and use my oil and filter even though they sell the same Castrol Syntec for much higher. We left the engine to drain for about an hour and 15. My 2000 S recently passed the 60K mile mark without any major issues. The only unscheduled repair has been a new throttle body and replacing an 02 sensor. That's it. This is not a daily driver and I change teh oil every 7K miles or so. So my first post Mobil 1 impressions of CS: Something has definitely changed. I've had m1 oil changes before and didn't really notice a difference. After a couple of days of the oil running I'm strongly inclined to say the engine runs much crisper and smoother after a CS oil change than a M1 oil change. It's most noticeable from a standing start. The revs seem to be "flawless" if I can put it that way. Almost as if the engine is not working as hard to get the car up to 70mph or so. Obviously this is not a very scientific analysis. I had some concerns about introducing a new mixture into the engine while there was still some M1 in there. A friend also made a switch from a different oil to CS and soon noticed some strange looking oil residue near the oil cap that had a tan/greyish color about it. The engine also sounds quieter when idling. I'm wondering if this more to do with changing the weight of the oil from M1 0-40 or the Boxster engine just liking Castrol's mix better. Going forward I'm going to change the oil every 5K miles to take advantage of the lower price for Castrol Syntec.

Two weeks ago I did the same thing with my 01. Changed to Castrol Syntec 5 W 40 from Mobil 1 since new. What I noticed almost immediately after the change was how quiet it was on startup. Significantly quieter. I guess I never really paid attention or noticed the little noises it made on starting, but now that it doesn't, it's very apparent now for the LACK of noise. I haven't seen any changes like you mention of it being quicker to accelerate or crisper, but it does seem to run smoother. All of which I suppose could be attributed to the heavier weight oil. I also got my oil from Advance. 10 qts was 37.10. No free K&N...you had to buy one oil filter for every 5 qts to get that price. Since they didn't have any Boxster filters (well.. they would order one for around $30 so I said no thanks!) I got a filter for wife's car and son's truck and still came out ahead. Total invoice. 10 qts oil, two filters, tax, $53.78!! not bad, considering the oil alone would have been around $70 including tax! Bob

The next time they are running a special on the Castrol please feel free to post about it! That's a great price on that oil.

Is that a group III or IV based oil? I'm finding it's hard to find which are true synthetic and which are extra-refined group III as they're both called "synthetic".

I don't think syntec is actually a full synthetic, but instead a blend. Not sure it makes that much difference if it is a good oil, but still. There's a guy on another board that has over 214k miles on his 02 Boxster, and all he's used was Mobil 1 0W-40, so M1 can't be that bad.

The bottle says "Full Synthetic". Could it have dino in it and still be cosidered full synthetic? I don't know the answer. But it's on Porsche's approved oil list. That was good enough. Plus, considering all the discussion about the formula change to Mobil 0w40 (most of which appeared to be negative) and the number of folks changing, or considering changing, to something else, that was enough to sway my decision to change. I don't THINK the price was a special.. although it could have been. I didn't see anything advertised about it.. the clerk just told me about price if i bought filters. Filters were discounted too! Bob

Found my answer: http://motorcycleinfo.calsci.com/Oils1.html Castrol's product is a Group III based oil. By the way, when people talk of Mobil 1's formulation change, they are talking about the fact that they went from group IV to group III. Not all Mobil 1 versions are made of the same base stock. I believe the some of the extended products are group IV.

What??? I have NO idea what that means! And neither the inclination nor the time to do the research to find out! I'm not bashing you, I just don't understand and, not being an engineer, not sure I would grasp the significance of it if I DID do the research. So...in layman's terms what does that mean? Is there any significance to me, the user, in what that says? Bob

If you read through the sections of that link explaining the differences in the oil base stocks, it should answer your questions. In short, under most normal driving, group III synthetics are fine but not the best you can buy.

Against my better judgement and lack of time I read that article (or the part you referenced). Last sentence in the section reads: "To the best of my knowledge, Delvac-1, AMSOil, Redline, and Motul 5100 are the only oils made from pure traditional synthetics." Accordingly, one would assume that Mobil 1 is NOT pure synthetic. The introduction paragraph reads: "I am not a lubrication, filtering, chemical or mechanical engineer. I have a degree in engineering, but I studied electrical engineering. I now study physics. You may feel free to question my abilities to gather facts and draw conclusions in the area of oils and filters. In any case, this is a write up of what I learned in about 75 hours of research on this topic. My only interest is having my motorcycle run forever, never break, and be easy to maintain." Based on his admitted lack of knowledge about the subject, I give virtually no credence to the remaining conclusions in the article. Bob

^ doesn't the mileage have a large role in the peformance of the oil? What I mean is if you change the oil frequently, well before it breaks down, is there really little difference between a $5 and a $10 synthetic? I tend to think it better to change your oil frequently with a respectable Porsche approved oil than to leave a more expensive oil in there for a longer period, long enough for it to matter.

So do more research and reach your own conclusions. I can tell you he is accurate in the descriptions of the oil make-up. bobistheoilguy.com is a very extensive resource to start out with.

ARRRRRRRRRRR... I don't have the time, inclination, or KNOWLEDGE to do the research. You brought up a distinction which I admitted I don't know anything about, let alone the significance of it. And I asked you to explain WHY that was important. You pointed me to a source. Your source is severely lacking in credentials, by his own admission. Why would I believe someone who has a grand total of 75 hours of internet research on the subject??? Hell I can do that!!! If I was going to do my own research I'd need to devote hours and hours to it to derive any benefit, maybe. IF I could tell what it was I was actually researching. Time I don't have. Nor, as I've repeatedly stated, the knowledge of oil. Every discussion I've read here and elsewhere dives into technical lingo, rating of this and that property, etc etc. And I keep saying, so what??? What significance do all these things have, to me the user??? NO ONE will answer me. Everyone keeps saying.. do research. GRRRRRRRRRRRRRRRR NO I'm NOT going to do futile research to no end!!!. I've given up. And I've given up reading these oil discussions. So there! I'll use Castrol Syntec 5w40 and drive my Boxster for 200,000 miles! Love Bob

Wow, I'm glad it's not my job to spoon feed you information. Maybe MNBoxster or Lil Bastard will come along and regurgitate some information for you.

Scuse me? That was rude and totally uncalled for. You apparently think everyone on this board is an engineer who might understand what the hell is being discussed. That's obviously an erroneous conclusion. As for spoon feeding, how much do you know about tax law? not much?? hope you can do good research on your own when you need to, and come up with appropriate conclusions regarding your chances for success, since you obviously think everything one needs to know in on the internet and is there for the taking.

Now boys, Castrol does make a full synthetic the ad is in the attached youtube. http://www.youtube.com/watch?v=jewzO6fkPDg

I think on my next change it's going to be Lubri Moly....

LOL. good one Bob

I don't get those ads, aside from being funny, what does a Scottish man wearing a tartan hat and neck tie have to do with Castrol?

Time for you to tone it down. In short, Group 4 and 5 synthetics are really on only oils made from full synthetic base oils. Whether you need a group 4 or 5 is a matter of opinion. Do what you need to do and watch your tone. Thanks BL