What I like most about your post is not the unequivocal "Wrong" but the way you back it up with well thought out statements like "Think about it" and even some scientific terminology like "coax it up." How can I argue with that.
I did a comparo once. I drained the oil normally from my from E30 M3 and with a topside oil changer on a friend's E30 M3. I then stuck the topside oil changer into my car and pulled the drain on his car. The topside oil changer was able to get out a bit more oil that was left over. When I pulled the drain on the other car, not a single extra drop of oil came out. Made me a believer the top side changers are better.
There you go. I will still prefer to pull the plug, especially on cars that go a long time without an oil change, but looks like the topside changer should be at least equal for a car whose oil is still nice and fluid.
When I said that topside extraction gets as much or more than gravity drain on BMW 6's I wasn't speculating, I tested it. Depending on how level the surface is or how the car is raised for a gravity drain you can get up to a 4oz variation either way. But on a relatively level surface such as a garage the extractor gets more. In practice, I test it routinely because every other oil change I follow up my topside extraction with pulling the magnetic drain plug I installed to check and clean it.
That is good practice with the metal drain plug. Also, as mentioned before, getting the car in the air every 3-6000 miles is a good idea.
Yeah, I also did my own test. I bought a milkshake and "coaxed" it all up with a straw there was still some residual milkshake left after I finished. I then bought another milkshake and poked a hole in it. I just let the milkshake sit, no energy expended. Eventually all of the milkshake was drained out of the cup. Hey, it's about as scientific as your test....
Either way of draining the oil will still leave the oil in the Vanos lines. I use a topside extractor, make sure you open the oil filter canister and let it drain before extracting.
in my old explorer I used to be able to change the oil by just reaching under lol. changed my oil today with just a cheap set of ramps.
A word about lifts... First of all, I'm not sure I would trust those two post lifts like I saw in the photos (or maybe the photo just doesn't show any other supports for the lift). That's roughly 1.5 to 2 tons of German engineering that could down on your head at any time. I don't know what's holding up the car's back end, but being crushed under a BMW is not my idea of going out in style! Secondly, a lift can do a lot more than just aid an oil change. Practically the whole drivetrain and both the front/rear ends become very accessible. You can pull the tranny without having to remove the engine, change the driveshaft, access the rear fuel tank, etc. Definitely a worthwhile investment if you can afford it. I've seen these lifts priced as little as $1,500. As for this whole drain from the bottom/extract from the top debate, here's a more scientific test, although with some models it will be more mechanically involved: Do two tests. Remove the oil pan (the lower one if your car has two like mine does) and clean it. Fill it with fresh oil. On the SECOND oil change after removing the oil from either method, remove the oil pan again and check for sludge build up (photograph it if possible). Clean the oilpan. Repeat on the second oil change and change your oil using the OTHER method. Remove the oilpan again. Check for sludge and photograph. Alternate methods include using two identical cars that see the same amount of use, and run a side by side comparison test instead. This way, the oilpans only have to be removed twice instead of three times. Or we can settle it by bouncing the question off a certified BMW Mobile Tradition tech (I say Mobile Tradition because most of the newer cars are designed to discourage DIY oil changes -- especially the new E92 M3, which made it almost impossible for a DIY'er change their own oil, since the car has to be connected to the GT1 computer to run the auxiliary oil pumps).
I would second the that view of two posters. I want to get a four poster. One, I just feel more comfortable with a four poster than a two, and second, I want to store another car under the car I keep on the four poster.
Two post lifts are industry standard in the automotive repair business because of access to the underside of the car is unrestricted. A 4 post lift is usually a drive on, meaning you need extra equipment to lift the car to get the wheels off, but they have their advantages. They require less overhead space for installation because there is no crossbrace needed above the posts. They are more stable for the average joe to use. Many do not require permanent installation, and some even come with casters so you can roll them around. You can buy a drip tray to store one car above another. They tend to be cheaper because they do not need as much steel to support the car. They are lighter for the same reason. All in all, perfect for home use by a serious auto hobbiest when equipped with the support to remove the wheels from the car. Hmm. I think I just talked myself into getting one once I get my garage finished.
Long story short...there is nothing wrong with the two-posters. They are rated at like 7 tons. Some are rated at 9 tons! I've used a two-poster for years! And btw...you dont need as much support under the rear end of the car because ~65% of the weight of the car is at the front.
Oh yes, 2 post lifts are just fine. Been using them for years. However, you have to know how to set the car on the lift. If you do it wrong, you can lose the car over one end or the other. Can't happen on a 4 post. Most BMWs are closer to 55% front/45% rear. In fact, front drive cars are much more dangerous to put on a 2 post lift because they are tippy. You set the lift wrong and take the rear wheels off, and bad news. Conversely, saw a lovely writeup on a guy that had a Lotus dropped off a lift by an incompetent tire shop. They took the front wheels off and back it went. Totaled the car.
I've had my oil pan off. No sludge. The caveat is I dont have any sludge in my engines. What I dont understand is: 1) Why someone would think that sludge cant be vacuum extracted. 2) Why people think the drain plug gets more oil out than vacuum extraction. IF there something in the pan that can be vacuumed out it will clog the extractor and you can pull the plug. IF that is the case you have a serious issue.
Since the new cars have no dipstick tubes, the point is completely moot for them. Sludge won't flow to the pickup tube on a vacumm pickup IF it is too thick, but MIGHT flow out the drian plug due to the flow of hot oil pulling it out. Viscous and cohesion forces MIGHT pull the sludge better with the faster flow rate. No definites there. I still prefer the old fashioned method, but for my dad's old 300SD, the topside would be fine because diesels don't really ever build up sludge. They just blacken the oil with soot. If you have sludge, you have problems and really should be changing the oil more no matter how you do it. The piddling little bit that may or may not be left over with either method won't matter if it is changed often enough. PS, found the pics online: Fell off lift More pics
