improved fuel economy from switching x-40 to x-30?

[rmz]

hey guys,

my 98 bmw 740i takes (according to owner's manual) either 5-30 or 15-40. currently running M1 0-40. if i was to get my oil changed at the dealership (NEVER WOULD) they would put 5-30 in bc that's what they have most available.

1) since either is "acceptable" is there any benefit to either grade? would i get any increased fuel economy from a x-30?

2) also, while we're talking about my car should i use a different grade in summer (put the 0-40 in for winter)... like a 10 or 15-40? is it best to go with smallest viscosity range for climate?

3) with my discount i can get "bmw" oil for just over $5 a quart, should i go that route? (from what i understand it's just a castrol product in a BMW bottle) or what oil should i use? M1? one of the fancy one's? edge?

thanks!

 

[Steve S]

a tenth or 2 tenths of a mpg.

 

[rmz]

Originally Posted By: Steve S
a tenth or 2 tenths of a mpg.


i figured it couldn't be much of a gain... but had to ask since i know honda went to 5-20 from 5-30 for fuel efficiency reasons...

is there any benefit to a "thicker" oil? should i go with what's cheaper? should i go with thickest acceptable or thinnest acceptable?

 

[MGregoir]

Thicker oils offer more high temperature protection (if you see high bulk oil temperatures) and better ring sealing.

0W-40 or 5W-40 is probably about as ideal as it gets for that car. An ACEA A3 rated, BMW Longlife-98 or 01 oil will do everything that car needs. Mobil 1 0W-40, Quaker State Q/Pennzoil Platinum 5W-40 (Shell Helix Ultra 5W-40 rebranded) or Castrol Syntec 0W-30 European Formula would all be suitable oils for your application and likely return about the same mileage.

 

[rmz]

Originally Posted By: MGregoir
Thicker oils offer more high temperature protection (if you see high bulk oil temperatures) and better ring sealing.

0W-40 or 5W-40 is probably about as ideal as it gets for that car. An ACEA A3 rated, BMW Longlife-98 or 01 oil will do everything that car needs. Mobil 1 0W-40, Quaker State Q/Pennzoil Platinum 5W-40 (Shell Helix Ultra 5W-40 rebranded) or Castrol Syntec 0W-30 European Formula would all be suitable oils for your application and likely return about the same mileage.


thank you very much for this info... good to know

only question left is whether it's better to go with a higher xw-40 (10w or 15w) that meets the same requirements? is it better to get a smaller viscosity range? i'm assuming less additives (that can break down) are used in achieving a smaller ranger than 0-40...

 

[mva]

The BMW 5W30 oil is good stuff. There are several threads here to prove it; here is an example with photos and UOAs:

http://www.bobistheoilguy.com/forums/ubb...173#Post1343173

That said, I just got a great deal on Maxlife 10W30 full sythetic which is BMW LL98 and LL01 approved. I can't wait to try it in my Z3M but I only have 4000 miles on the Castrol Syntec 5W40 thats in the car now.

 

[MGregoir]

15W-40 good brand HDEO (Shell Rotella, Mobil Delvac or Chevron Delo) would be fine oils to use in the summer, but I don't know your commute/drive either. A 0W-40 or 5W-40 will return better mileage than 10W-40 or 15W-40 on short trips, the 15W-40 will likely cost mileage, and non-synthetic 10W-40 (there is very little synthetic 10W-40 out there) will break down worse than a synthetic 5W-40 or 0W-40.

5W-40 and 0W-40 oils are generally higher quality synthetics made for European specifications that demand longer lifespan between drain intervals, are tested more strenuously, and tailor-made for higher performing engines or hard use (think Autobahn).

Porsche racing engines and Honda IndyCar engines use off the shelf Mobil 1 0W-40, and in some engine families that same oil is also recommended for 18,000 mile oil change intervals.

The other end of the 5W-40 spectrum are heavy duty oils designed for diesels, which must provide protection in heavily loaded turbocharged engines that produce a large amount of combustion byproduct, and be compatible with a wide range of engines in both gasoline and diesel fleets. Those oils are as close to a "universal" four stroke reciprocating engine lubricant as you can find and are commercial grade with some of the most advanced R&D and strenuous testing from a wide variety of manufacturers to back them up.

 

[rmz]

Originally Posted By: MGregoir
15W-40 good brand HDEO (Shell Rotella, Mobil Delvac or Chevron Delo) would be fine oils to use in the summer, but I don't know your commute/drive either. A 0W-40 or 5W-40 will return better mileage than 10W-40 or 15W-40 on short trips, the 15W-40 will likely cost mileage, and non-synthetic 10W-40 (there is very little synthetic 10W-40 out there) will break down worse than a synthetic 5W-40 or 0W-40.

5W-40 and 0W-40 oils are generally higher quality synthetics made for European specifications that demand longer lifespan between drain intervals, are tested more strenuously, and tailor-made for higher performing engines or hard use (think Autobahn).

Porsche racing engines and Honda IndyCar engines use off the shelf Mobil 1 0W-40, and in some engine families that same oil is also recommended for 18,000 mile oil change intervals.

The other end of the 5W-40 spectrum are heavy duty oils designed for diesels, which must provide protection in heavily loaded turbocharged engines that produce a large amount of combustion byproduct, and be compatible with a wide range of engines in both gasoline and diesel fleets. Those oils are as close to a "universal" four stroke reciprocating engine lubricant as you can find and are commercial grade with some of the most advanced R&D and strenuous testing from a wide variety of manufacturers to back them up.


thanks for the info, i'm really glad i found this forum

so what i gather is i should be fine with what i have... no reason to change from M1 0-40 unless good deal on something else... only prob is M1 0-40 is not sold in 5qt jugs and is not cheap whereas syntec and a lot of others are sold cheaper in jugs at walmart

as for my driving habits: lots of short trip driving during the week for work and errands, and 4+ highway trips a week of 25 miles each way to see the girlfriend

currently changing oil every 5K

 

[MGregoir]

If you have the engine run while driving at least a half hour once a week, you greatly extend the oil lifespan abd it cancels out some of the short tripping. Mobil 1 0W-40 at 5,000 miles is probably very safe and working for you, a UOA may tell you where you stand for oil life if you run the same conditions all the time.

You may be able to extend your drains, or another option would be to find a less expensive oil and do a couple of used oil analyses to trend what the oil's life span is so you can set your intervals there. You will pay $35 initially to get the analysis done, but it can save you maitenence dollars over the long term.

 

[blaze1]

I recently switched too m1 0w40 to castrol to GC 0w30, and unlike the times where i felt better mpg filling with fresh mobil, I don't see a big difference after switching to GC.

Does seem to run smoother on my fsi though

 

[JAG]

In my 1.8T GTI, I seemed to get better gas mileage with M1 0W-40 than GC.

 

[rmz]

Originally Posted By: blaze1
I recently switched too m1 0w40 to castrol to GC 0w30, and unlike the times where i felt better mpg filling with fresh mobil, I don't see a big difference after switching to GC.

Does seem to run smoother on my fsi though


you noticed improved fuel economy after oil change? wow... by how much? i could really appreciate some of that right now, i'm only getting 17-18 overall with my bimmer