Oil Consumption

[Gene K]

Thought I would put most modern oil consumption complaints in perspective.

Rolls Royce used to say you could expect about 1% of the oil use as gasoline use.

So at 10 mpg you could expect to burn about 1 gallon of oil every thousand miles.

 

[MRC01]

... Rolls Royce used to say you could expect about 1% of the oil use as gasoline use. ...

Ah, but in what kind of engine? 1:100 is about 4x higher than I'd expect from a car.
A car that gets 30 mpg and burns 1 quart of oil every 3000 miles is 1:400.
Maybe Rolls Royce was referring to a Merlin V-12?

This is an interesting way of expressing it. In aviation, a typical healthy Lycoming engine like the O-360 burns 1 quart of oil every 17 hours, plus or minus. I used to think of that as "burning more oil than a car". But if you do the math it's actually about the same. The engine consumes about 8 gallons per hour of gasoline, so in 17 hours it burns 17*8*4 = 544 quarts of gasoline and 1 quart of oil. That is 1:544 which is comparable to most cars.

 

[kschachn]

Do you have a link to this Rolls-Royce statement? It sounds like it’s from about 1910.

 

[vavavroom]

I'm also thinking aircraft engine.

 

[double vanos]

At one gallon to every thousand miles you’re approaching two stroke levels of consumption…..
Wow

 

[kschachn]

I'm also thinking aircraft engine.

An old one maybe. Looking it up, today’s engines are far less than that. Even our old Diesel-9s had a limit of 1/2 quart per hour.

 

[Gene K]

Do you have a link to this Rolls-Royce statement? It sounds like it’s from about 1910.

I've seen it attributed to an old manual sometime after total loss but prewar. Sorry no actual verification.The post was made in an attempt to make the guys with modern engines that consume a quart every 1000 mi feel a bit less.... I don't know.... victimized?

 

[kschachn]

I've seen it attributed to an old manual sometime after total loss but prewar. Sorry no actual verification.The post was made in an attempt to make the guys with modern engines that consume a quart every 1000 mi feel a bit less.... I don't know.... victimized?

Okay.

 

[doublebase]

That’s too high. I think most manufacturers put somewhere around a quart per 1,000-1,500 miles (something like that). Which I think is too much anyway. I really think it comes down to what YOU feel is acceptable. It’s your car. For me, adding three quarts in a 5,000 mile interval is too much. In my mind that means you have a problem. And I also feel it depends on the actual mileage of the vehicle - you’d expect a vehicle with higher mileage to consume more than say a vehicle with 50,000 miles on it. Do you put up with it when your vehicle has 250,000 miles and kind of push it along until you reach 300,000-400,000 miles? I mean, in my opinion after a certain mileage point all bets are off anyway. You do what you can to keep it running and don’t expect it to still be running perfect. I bet there’s a ton of people that will gladly put a couple quarts in an interval if it means saving a car payment. I would. But I’m doing that at lower mileage. That’s just me.

 

[PimTac]

I've seen it attributed to an old manual sometime after total loss but prewar. Sorry no actual verification.The post was made in an attempt to make the guys with modern engines that consume a quart every 1000 mi feel a bit less.... I don't know.... victimized?

Sometime after total loss but prewar? What era was this?

Which modern engines consume a quart every 1000 miles?

 

[Gene K]

Sometime after total loss but prewar? What era was this?

Which modern engines consume a quart every 1000 miles?

About 100 years ago give or take and it was a gallon not a quart.

As to modern engines that consume a quart every 1000 mi try a GT350 Mustang. All joking aside Rotary Engines do by design.

 

[PimTac]

About 100 years ago give or take and it was a gallon not a quart.

As to modern engines that consume a quart every 1000 mi try a GT350 Mustang. All joking aside Rotary Engines do by design.

Who still makes a rotary engine?

Your topic is really convoluted.

 

[Gene K]

Who still makes a rotary engine?

Your topic is really convoluted.

Mazda MX30 EV with Range Extender (Japan only initially) uses a Rotary.

 

[vavavroom]

An old one maybe. Looking it up, today’s engines are far less than that. Even our old Diesel-9s had a limit of 1/2 quart per hour.

A very old one. I believe a Merlin consumes about 0.02 lbs of oil per hp per hour. At about 1,000 hp that's 20lbs or 2.75 gallons or 352 oz of oil consumed per hour. That comes to almost 1/10 oz of oil consumption per second.

If the suggested oil-fuel consumption of 1% of gasoline use checks out the Merlin engine should consume as much as just under 1/10 oz per second. This number seems a bit high to me. Maybe someone can look up the Merlin's fuel consumption. These engines lose a lot of oil via the breathers. No idea if the 1% figure includes this oil loss. Oil consumption of the Merlin has been stated as up to 1/8 oz per second.

 

[MRC01]

Who still makes a rotary engine?

The 13B-REW in my '95 RX-7 (the twin turbo version) injected oil with fuel, but only at high throttle/load/RPM. If you drove it like a grandma (which nobody did), it didn't burn oil. If you drove it the way it was meant to be driven, like in SCCA events, it burned about 1 qt every 1000 miles. Not by leaking but by design.

 

[MRC01]

... Maybe someone can look up the Merlin's fuel consumption. ...

The CFI for my very limited P-51 time flight planned on 80 gals/hour for typical flights, cruise with some light acro. For a ballpark max, divide 1600 HP by 13 gals / HP / hour you get 123 gals/hour, which would be at full throttle/rich mixture.

 

[RDTaylor]

That’s too high. I think most manufacturers put somewhere around a quart per 1,000-1,500 miles (something like that). Which I think is too much anyway. I really think it comes down to what YOU feel is acceptable. It’s your car. For me, adding three quarts in a 5,000 mile interval is too much. In my mind that means you have a problem. And I also feel it depends on the actual mileage of the vehicle - you’d expect a vehicle with higher mileage to consume more than say a vehicle with 50,000 miles on it. Do you put up with it when your vehicle has 250,000 miles and kind of push it along until you reach 300,000-400,000 miles? I mean, in my opinion after a certain mileage point all bets are off anyway. You do what you can to keep it running and don’t expect it to still be running perfect. I bet there’s a ton of people that will gladly put a couple quarts in an interval if it means saving a car payment. I would. But I’m doing that at lower mileage. That’s just me.

Hi all .I worked as a Auto technican for 30 yrs.If a car is Maintained from New using normal oil intervals In Canada 6000km no more,your car should not consume hardly any oil.If its a sports car pushing rpms or a pickup towing excessive loads yes a bit of oil ,maybe a quart between oil changes yes. I worked at Honda and around 2009 we had oil consumption issues in the 2.4 accords.Hondas fix was to try and brain wash customers that if you burned a liter of oil for 1500km it was normal, anything over that they would open a warranty claim.All BS.it was a design flaw that Honda would not own up too.i have had 24 vehicles ranging from domestic to Korean and Japanese,cars should not burn hardly any oil when using proper oils and right oil intervals.This new nainteance minder and getting 8000 to 13000km o your oil is no good for the engine,I have seen and witised it all.

 

[Eddie]

I've never had a vehicle since 1970 that used more than 1/4 quart per 5,000 mile oil change. Volvo, AMC 4.2L, Subaru 2.5L, Mazda 2.3 Turbo, Mazda 2.5L turbo. The 1,000 miles per quart is the limit that GM originally picked that value to consider a bad engine. I forgot which engine GM had the oil consumption issue that resulted in that value.

 

[Johnmpb]

One star thread Gene….

 

[alcyon]

My 80s car uses 200ml every 1000 miles for sump of 4L. Thats like 0.05% oil consumption.