A lot of big diesel engine operators use a formula to schedule oil changes .I'm not smart enough to figure it out so I change the oil when sent out to change it.
Oil Change Formula
- Thread starter TooSlick
- Start date
- Status
Several new car manufacturers (BMW for one) calulates the oil drain interval with their onboard computers and lights the change oil light on the dash. Does anyone know if this is this same formula used by the manufacturers?
'01 Audi A4 1.8TQ
21 mpg
3.7 qt sump
108 Ci
170 hp
Using TooSlick's formula, this gives 5,922 mile oil change interval, much lower than manufacturer's recommended 10K mile interval.
Interestingly, when I had my M1 5w30 analyzed at 4,700 miles, Terry suggested that this oil was good for about 6,000 miles in my engine.
21 mpg
3.7 qt sump
108 Ci
170 hp
Using TooSlick's formula, this gives 5,922 mile oil change interval, much lower than manufacturer's recommended 10K mile interval.
Interestingly, when I had my M1 5w30 analyzed at 4,700 miles, Terry suggested that this oil was good for about 6,000 miles in my engine.
Some of these mechanisms are smarter than others. On some cars, the light comes on strictly based on number of miles since the last interval. On some others, miles as well as number of rpms is factored in (i.e. how hard the engine was driven). Yet on some others, there are in fact sensors in the engine that measure oil quality (a simplified version of what you do when you send out your oil sample to Blackstone) to determine when to light up the "change oil" icon on the dashboard.
Patman
Staff member
This formula has got me so confused I've decided to go back to 3k intervals!
(just kidding)
(just kidding)
Norm, I suspect TooSlick's 27 mpg is achievable with mostly highway driving. Also, the quattro system on his TT is haldex-based, which means it works like a FWD vehicle most of the time. On the other hand, the quattro system on my A4 is Torsen-based, which means it's constantly AWD. This has a negative effect on gas mileage. I stated 21 mpg because I mainly drive in the city (lots of stop-and-go bumper to bumper traffic). If I take it easy on the highway, I can get about 28 mpg.quote:
Originally posted by Norm Olt:
I find it interesting that TooSlick's 225hp version of this engine with a capacity of 4.8 qts. but gets 27 mpg while QuatroPete's 170hp version with a 3.7 qt. sump (?) gets only 21 mpg.
Right.
Check out these used oil analysis results I just posted from the 170hp A4 turbo engine runningMobil1 5w30 for 10K miles.quote:
That Too's would be 25% greater is no real surprise to me: that the manufacturer's 10K recommendation will leave the door open to possible oil-related problems down the road (read this as "WHEN THE WARRANTY HAS EXPIRED")is no real shocker either!
[ March 06, 2003, 05:59 PM: Message edited by: Quattro Pete ]
quote:
Originally posted by Norm Olt:
p.s. I would look into adding to the overall lubricating capacity of any turbocharged high output motor in any vehicle I owned: oil cooler, extra filtering, etc. might pay huge dividends if one was concerned with the long term life of the engine IMHO...
I also let the turbo cool down by taking it easy the last mile or so and idle for about a minute or two before shutting off the engine.
The higher the specific output of the engine, the smaller the oil capacity, the more skewed these factors will be in this formula. Then add in mpg!
I find it interesting that TooSlick's 225hp version of this engine with a capacity of 4.8 qts. but gets 27 mpg while QuatroPete's 170hp version with a 3.7 qt. sump (?) gets only 21 mpg.
Both are turbocharged, right? That Too's would be 25% greater is no real surprise to me: that the manufacturer's 10K recommendation will leave the door open to possible oil-related problems down the road (read this as "WHEN THE WARRANTY HAS EXPIRED")is no real shocker either!
Some manufacturers have always gone with a larger capacity (Porsche "and jus' 'Cause it's Air-cooled"
), MB (8 quarts for a 4.2 liter), the original Acura Legend had an oil cooler, cartridge-type filter and 6 quarts for a 2.5 liter motor, etc. Other manufacturers seemed to have gone the other way.
Specific output now-a-days is almost astronomical!
Remember when ONE hp per cubic inch (as in a fuel injected Chevy) was unheard of? Cars today (and oils, too!) are, on the average, so much more powererful, efficient, reliable and non-polluting that those "Good ol' Times!" are now. Too bad the cost of a new car or truck has gone through the roof!
Fortunately there are many great used vehicles out there just waiting to be snatched up by knowledgeable buyers, to be treated right and ready to run for years.
p.s. I would look into adding to the overall lubricating capacity of any turbocharged high output motor in any vehicle I owned: oil cooler, extra filtering, etc. might pay huge dividends if one was concerned with the long term life of the engine IMHO...
I find it interesting that TooSlick's 225hp version of this engine with a capacity of 4.8 qts. but gets 27 mpg while QuatroPete's 170hp version with a 3.7 qt. sump (?) gets only 21 mpg.
Some manufacturers have always gone with a larger capacity (Porsche "and jus' 'Cause it's Air-cooled"
Specific output now-a-days is almost astronomical!
Remember when ONE hp per cubic inch (as in a fuel injected Chevy) was unheard of? Cars today (and oils, too!) are, on the average, so much more powererful, efficient, reliable and non-polluting that those "Good ol' Times!" are now. Too bad the cost of a new car or truck has gone through the roof!
Fortunately there are many great used vehicles out there just waiting to be snatched up by knowledgeable buyers, to be treated right and ready to run for years.
p.s. I would look into adding to the overall lubricating capacity of any turbocharged high output motor in any vehicle I owned: oil cooler, extra filtering, etc. might pay huge dividends if one was concerned with the long term life of the engine IMHO...
Pete,
How many qts of oil does you engine hold? I think Norm's just giving various ways to increase the capacity. My '99 Saab turbo holds 4L, but the '03s just jumped up to a 6L capacity, along with the addition of the latest version of GM's Oil Life Monitor (it gives a "miles remaining" readout). If I wanted to bump my capacity up to that, I'd have to either add a bypass filter or an oil cooler (or both?). Of course, you could always place the cooler in a shielded location, so it maintains oil temp rather than reducing it. That way, you'd get the volume increase without changing the operational temps.
BTW, has anybody heard about Delphi Electronic's latest OLM? I've heard it actually does on-board OA to determine oil life.
How many qts of oil does you engine hold? I think Norm's just giving various ways to increase the capacity. My '99 Saab turbo holds 4L, but the '03s just jumped up to a 6L capacity, along with the addition of the latest version of GM's Oil Life Monitor (it gives a "miles remaining" readout). If I wanted to bump my capacity up to that, I'd have to either add a bypass filter or an oil cooler (or both?). Of course, you could always place the cooler in a shielded location, so it maintains oil temp rather than reducing it. That way, you'd get the volume increase without changing the operational temps.
BTW, has anybody heard about Delphi Electronic's latest OLM? I've heard it actually does on-board OA to determine oil life.
Yeah, but keep in mind TS's formula is for Amsoil's premium full syn, & I think Amsoil recommends a 3x life for this oil. So that would be 15k/9k for the Ford, & 22.5k for the Jeep, w/o factoring in the variables of the formula.
I hadn't run the numbers, but I think we start to lose it looking at truck engines. The 4.7 in the Jeep above was a good example.
For another, look at my F150's with the 4.6l:
Oil Sump: 6 qts
Engine Size: 281 ci
Engine HP: 220 hp
Engine Torque: 290 ft-lbs
97 2wd: 17 mpg
99 4wd: 16 mpg
600*(6/5)*(281/220)
600*1.2*1.277 = 919.4
For the '97:
919.4*17 = 15,630 miles
The '99:
919.4*16= 14,710 miles
If I sub in the torque numbers, I get 11,860 miles and 11,162 miles, still a little long in my case. Ford calls for a 5,000 mile interval and a 3,000 mile severe duty interval.
My Cherokee with the 4.0l engine would have an interval out of this formula of nearly 18,000 miles! Even in 1988, the suggested interval is 7500 miles!
For another, look at my F150's with the 4.6l:
Oil Sump: 6 qts
Engine Size: 281 ci
Engine HP: 220 hp
Engine Torque: 290 ft-lbs
97 2wd: 17 mpg
99 4wd: 16 mpg
600*(6/5)*(281/220)
600*1.2*1.277 = 919.4
For the '97:
919.4*17 = 15,630 miles
The '99:
919.4*16= 14,710 miles
If I sub in the torque numbers, I get 11,860 miles and 11,162 miles, still a little long in my case. Ford calls for a 5,000 mile interval and a 3,000 mile severe duty interval.
My Cherokee with the 4.0l engine would have an interval out of this formula of nearly 18,000 miles! Even in 1988, the suggested interval is 7500 miles!
I'd like to thank everyone for their comments on this idea, which is still in it's early stages. This formula does assume the engine has been well maintained and is running normally. It is also predicated on the fact that the OEM recommendations for conventional oils are reasonable - I specifically don't think this is the case for the 3.0L, Toyota V-6. So you would have to adjust the formula accordingly. I have attempted to account for variations in driving conditions by making fuel efficiency one of the key variables, but perhaps a further "knockdown" factor is needed for very severe conditions. I'd also like to add that this was determined using gas engine passenger cars, but I think the idea has wider applicability ....
Most of the calculated drain intervals I've seen posted above seem achievable with the Amsoil 5w30/10w-30/10w-40, based on my past experience.
Thanks again for your comments ...!
TooSlick
Most of the calculated drain intervals I've seen posted above seem achievable with the Amsoil 5w30/10w-30/10w-40, based on my past experience.
Thanks again for your comments ...!
TooSlick
Pete:
I was suggesting increased system capacity vs. any need for additional cooling, as a 3.7 Qts. system can be increased by almost 25% by adding an additional 3/4 Qt. filter and about 6 oz. in the lines. Thanks for the info regarding the different AWD systems: that was new to me. The results posted vis'-a-vis' your friend's 170hp Turbo with M1 5w30 were spectacular, indeed!
We have a Subaru SVX, 3.3L non-turbo, 230hp with a 6 quart system capacity. The mileage figures you are quoting seem to be just about what we get in this vehicle, both in mixed , city only & highway. The transmission on this vehicle is the point where additional capacity, cooling & filtration are sometimes needed, although I've been very lucky with mine. I still get my oil & filter changed for free every 3K from the dealer so I've really never anticipated the need for either analysis or extended intervals. Am going to give it an Auto-rx treatment as I'm approaching 100K on a motor that has never been opened up: not even a valve cover gasket.
I'm still very impressed with the 225hp version's mileage, even if it is primarilly highway miles.
I was suggesting increased system capacity vs. any need for additional cooling, as a 3.7 Qts. system can be increased by almost 25% by adding an additional 3/4 Qt. filter and about 6 oz. in the lines. Thanks for the info regarding the different AWD systems: that was new to me. The results posted vis'-a-vis' your friend's 170hp Turbo with M1 5w30 were spectacular, indeed!
We have a Subaru SVX, 3.3L non-turbo, 230hp with a 6 quart system capacity. The mileage figures you are quoting seem to be just about what we get in this vehicle, both in mixed , city only & highway. The transmission on this vehicle is the point where additional capacity, cooling & filtration are sometimes needed, although I've been very lucky with mine. I still get my oil & filter changed for free every 3K from the dealer so I've really never anticipated the need for either analysis or extended intervals. Am going to give it an Auto-rx treatment as I'm approaching 100K on a motor that has never been opened up: not even a valve cover gasket.
I'm still very impressed with the 225hp version's mileage, even if it is primarilly highway miles.
Yes, I missed that point completely. Thanks!
Yes, the EPA estimates on the 225TT are 20 MPG city, 29 MPG hwy, and 23 MPG combined. I wanted to say that it's thanks to its light weight, but after looking at the specs, it weighs in at around 3250 lbs - roughly the same as my A4. So, my only explanation for it is that while hwy cruising, it is basically a FWD car, so it consumes as much gas as any other FWD car. A 240hp V6 Accord can pull off similar mileage on the hwy, using only regular gas. The TT (and my A4) takes premium.
Why not use a timer? Get an oil analyis every 50 hours run time until an oil change is recommended, and change it every XXX hours from then on. Don't worry about any formulas. There are too many variables between engines.
Or, just monitor the amount of fuel burned.
Have an analysis performed every 10th full tank of gas until a change is recommended. Then, change oil every XXX gallons burned.
I believe that oil quality depends on driver, vehicle, fuel, and oil used. Everyone needs to be independent and have their own analysis done.
Or, just monitor the amount of fuel burned.
Have an analysis performed every 10th full tank of gas until a change is recommended. Then, change oil every XXX gallons burned.
I believe that oil quality depends on driver, vehicle, fuel, and oil used. Everyone needs to be independent and have their own analysis done.
While that may be true, I think we have seen that in general, it probably isn't a good idea to change and immediately go to such a long interval. My understanding, if I read right, is that the formula was to determine an "inital" sampling point to check on how the oil is doing. Call me crazy, but without prior analysis, doing over 10,000 miles for an initial fill probably isn't the best idea, IMHO. After trends have been established perhaps, but certainly not as a first check.
Norm,
I went out and looked at the trip computer and it registers 26.4 mpg for the last 10 tanks. Total mileage is @ 15,100 miles right now. This is the Audi TT quattro roadster,which weights about 3450 lbs. Most driving is a 25 mile commute to work at 55-70 mph.
I would agree with the point of having the engine fully worn in before trying to run these types of change intervals. I'd wait until you have 10k on the engine before running an extended drain. I will normally test a new engine running Amsoil for the first time after 10k-12k miles to see how the oil is holding up.
TooSlick
I went out and looked at the trip computer and it registers 26.4 mpg for the last 10 tanks. Total mileage is @ 15,100 miles right now. This is the Audi TT quattro roadster,which weights about 3450 lbs. Most driving is a 25 mile commute to work at 55-70 mph.
I would agree with the point of having the engine fully worn in before trying to run these types of change intervals. I'd wait until you have 10k on the engine before running an extended drain. I will normally test a new engine running Amsoil for the first time after 10k-12k miles to see how the oil is holding up.
TooSlick
- Status
Similar threads
- Sticky