Don't constantly top off an engine that burns oil?

[mclasser]

I've read posts on here saying to wait until the oil level drops to low before topping off a burner engine because doing so when the level, for example, is only at the halfway mark causes more consumption. Some also say not to overfill in a such engines since that too increases burning. The reasoning for the latter sounds like more oil = greater chance it'll slip past worn piston rings. What about the former? Why would you burn more if you top off at the halfway, or three-quarters mark, and not when low? You're still in the dipstick safe zone at all those points.

 

[Inspecktor]

Our Ranger uses some oil, and rate seems to be the same whether I top off when 1/2 quart low or 1 quart low.

 

[Hokiefyd]

Originally Posted By: mclasser

I've read posts on here saying to wait until the oil level drops to low before topping off a burner engine because doing so when the level, for example, is only at the halfway mark causes more consumption. Some also say not to overfill in a such engines since that too increases burning. The reasoning for the latter sounds like more oil = greater chance it'll slip past worn piston rings. What about the former? Why would you burn more if you top off at the halfway, or three-quarters mark, and not when low? You're still in the dipstick safe zone at all those points.

Some engines (due to a variety of reasons, including windage tray design or even dipstick/tube length error) appear to consume oil when plumb full, but don't consume oil if left a little low. In other words, "full" is actually overfull for that particular engine. In this case, keeping an overfull engine overfull will lead to continued oil use.

 

[Falken]

I usually check my oil during break at work to get out for fresh air (my version of a Smoke Break haha). I don't need any surprises as you never know when a Honda may start to suddenly consume oil (PCV, brand change etc...)

 

[racer12306]

I refill when it gets to a qt low, but I also check the oil about every other gas fill up, so I know the trend. Not worth the effort to put 1/4qt in an engine.

 

[Alex_V]

I've observed several engines, of different types, that do seem to consume oil faster the higher it is on the dipstick. I never monitored it scientifically or determined the specific cause, but I believe it's a valid scenario. In such cases I just strive to keep it at or above "add", only making a concerted effort to have it at "full" when I know I'm going to be working it hard. And given the state I've seen a couple engines' oil level in, which I monitored for 10,000 mi.+ after that incident (think 2 qts. low in both a Grand Caravan 3.8 and Buick 3800, with wayyy too many miles on straight conventional oil, and a 2-ton GMC ex-Coca-Cola truck w/454 that was 6 quarts from the full mark (!!!) and being beaten like a cheap mule hauling grain) the "add" mark isn't like the red mark at the top of your temp gauge. Do not misunderstand me, the add mark is there for a reason and running an engine's oil level below that puts all liability for a lubrication-related failure on the operator, but I don't consider it flirting with death to maintain the oil level in the lower half of the crosshatch if it reduces consumption.

 

[AntsinmyEyes]

If i check the oil and its not at the full mark then i top off until it is. Just thinking about my engine getting to the low mark gives me the heeby jeebies 😓

 

[BrocLuno]

Back in the day, I had a boss who had a pristine low mileage Buick V-8 Roadmsater (nail-head)and swore to never run that engine at full. He always just maintained it at the add mark. Said it would go a thousand miles at the add mark, but if it went to full, would burn a qt in less than five hundred... That car made him start doing it to all the vehicles. That bothered me, because there was less reserve if anything went wrong, or you were running the snot out of say the GMC pulling heavy boats from yard to yard over the grades... Cars and trucks fifty years more modern, generally don't exhibit the same problems as back then ...

 

[cmhj]

why risk it?

 

[Anwar2016]

A while back a poster had suggested to me to keep oil at add or low mark because the honda engine I have has blowby, due to worn rings,stuck rings etc. Some oil, oil vapors gets sucked thru the PCV into the intake and get's burnt. Not sure if the theory works to have oil at low mark and therefore less oil will get sucked thru the pcv. Planning on a catchcan set up soon.

 

[TFB1]

Originally Posted By: racer12306

I refill when it gets to a qt low, but I also check the oil about every other gas fill up, so I know the trend. Not worth the effort to put 1/4qt in an engine.

This^^^ I consider it insane to add half pint... I add at quart low and not even then if I'm gonna change in next 500 mi...

 

[demarpaint]

Currently I have nothing in my fleet that uses oil. When I did, if I had the hood open and the car needed 1/2 qt of oil I added it. If I had an open quart and it needed a pint, I'd add it.

 

[FCD]

All the cars i have ever owned have burned some oil to varying degrees but noticed no difference

 

[DuckRyder]

If you were supposed to add oil when it got below "full, the "full" mark would be the "add" mark...

 

[javacontour]

I guess it depends on WHY it's using it. My Protege5 will eventually get to 1qt/1000 miles, but not until 2 or 3k into the OCI. So for me to wait until it gets to be a quart low may not be the best choice. As it appears as the oil is more "consumable" once it gets a couple of thousand miles on it. I've driven about 1300 miles since my last oil change, and have noticed little or no consumption. By the time it gets to 2000-2500 miles, it might be down a quart. I add when it's 1/2 quart low, as it holds about 3.5L or 3.8 quarts, IIRC.

 

[barryh]

I never run the oil at max on the dipstick. While you have to be careful not to run below min, running at a lower level increases the air space which reduces crankcase compression and gives the PCV valve and easier time. That can reduce oil consumption. It will depend on the engine how much difference it makes. On my old 79 BMW motorcycle and all 70's or 80's BMW's it is the accepted wisdom that you run at half mast on the dipstick. BMW even issued a service bulletin that specifically says don't top up the oil until it reaches the min mark and then only add enough to take it part way towards max. In a further acknowledgment of the air space issue they then increased the sump volume.

 

[Popsy]

I always fill my cars to 3/4 full on the dipstick, just because that's practical, quantity wise. Never had a car that burned much oil though, but I actually notice on my old Mercedes 190E that when filled, oil was consumed to 3/4 full, then level barely moved.

 

[Anwar2016]

Originally Posted By: barryh

I never run the oil at max on the dipstick. While you have to be careful not to run below min, running at a lower level increases the air space which reduces crankcase compression and gives the PCV valve and easier time. That can reduce oil consumption. It will depend on the engine how much difference it makes. On my old 79 BMW motorcycle and all 70's or 80's BMW's it is the accepted wisdom that you run at half mast on the dipstick. BMW even issued a service bulletin that specifically says don't top up the oil until it reaches the min mark and then only add enough to take it part way towards max. In a further acknowledgment of the air space issue they then increased the sump volume.

I'm experimenting this with the honda accord. Keeping oil at add mark to see if less oil/oil vapors gets passed thru pcv valve to the intake. As you mentioned if crankcase pressure stays low, oil consumption will be reduced.

 

[69GTX]

I always add when down 8 oz. The designers planned on you have the full amount of oil they designed for. So that's what I do. I'm not concerned about "losing" 50c-$1 worth of oil shortly before an oil change.

 

[fdcg27]

The dipstick features a safe oil level zone that is typically either a quart or a liter from full to add. There is no reason to add oil as long as the oil level remains above the add line. The only concern with oil level is that it must be maintained at a level below which the oil pump pickup might suck air. The lower mark is intended to prevent this, with some considerable margin. In the case of my old BMW, the first half liter burns off noticeably faster than the next and the OM recommends not adding oil until the level reaches the add mark on the dipstick. Oil level is quite variable anyway, depending upon where and when you check it. I find those who top off a few ounces at a time pretty amusing. It's as though they don't understand how engines work or their lubrication requirements.