I got my car back from the shop with fresh oil in the engine. It's very transparent on the dipstick, but still discernible. If we consider the span from "H" to "L" on the dipstic as 100%, then the oil level appears to be 30% over the high mark. Long ago, I read that overfilling with oil is harmful because the crank shaft chops at the oil in the crankcase and causes it to foam up, thus becoming a poor lubricant. I don't know the accuracy of that, but I have read warnings against overfilling in other places. How much is too mucH? I don't want to hassle the shop to bleed off some oil if it's not too much. I also don't know the accuracy of the oil level because it seems that at that level, the oil level on the dipstick is not sharp; instead, it sort of tapers off and becomes spotty.
I also find black sludge at the bottom few millimeters of the dipstick, while all the rest of the oil is clear. Never saw that combination before. I am told that there was no sludge at the bottom of the oil pan. Is this something minor, to be ignored?
How long did you leave the car to cool off and stand before checking. After a run it can appear low because some of it is still in the engine, but sometimes, it can also appear high after a very fast run/long/hot run if you check it while it is still hot because as you say it foams up, and also because oil expands slightly when hot.
check it again first thing in the morning after it has had chance to sit overnight without running, then report back the level.
There are very few engines that need the oil level checking when hot, although 1 I know of needs it checking when actually running.
Dry sump system - racing engines. You check the oil tank.
They have a 'scavenge' pump to suck all the oil out of the crankcase and into a remote oil tank, and a pressure pump feeding from the oil tank to the bearings.
That way they can have a large oil supply without a huge oil pan hanging under the car to get damaged, and without the windage problems of an oil overfill getting into the crank area and getting aerated. In the middle of an endurance race it's easy and fast to dump in another quart or two at a pit-stop.
The span from "H" to "L" on the dipstick is not 100% of the crankcase capacity. It varies from car to car but ususally indicates anywhere from 1 to 3 quarts low. In other words, even with a dry dipstick, there could be a quart of oil remaining in the oil pan if the dipstick shows 3 quarts low.
Long ago, I read that
If you look at the shape of the oil pan, it is shaped more like an in-ground swimming pool than a bucket, The irregular shape means that level of oil shown on the dipstick will not be linear.
Overfilling the crankcase can cause the oil to foam and then become a poor lubricant. IMO, a half-quart over-filled isn't a problem, but if you have more than a quart over-filled, then some should be drained out.
If you see black sludge on the bottom of the dipstick, then there is sludge at the bottom of the oil pan or the oil was not thoroughly drained the last time it was changed. Actual semi-solid sludge than you can wipe off the dipstick is a bad sign. I would run some engine flush through, change the oil, repeat the process, then drop the pan and thoroughly clean it, or if you can't get the baffles clean, replace it. On the other hand, a little discoloration or stain on the metal dipstick is not anything to worry about.
"Tercel Owner" wrote: > I got my car back from the shop with fresh oil in the engine. > It's > very transparent on the dipstick, but still discernible. If > we > consider the span from "H" to "L" on the dipstic as 100%, then > the oil > level appears to be 30% over the high mark. Long ago, I read > that > overfilling with oil is harmful because the crank shaft chops > at the > oil in the crankcase and causes it to foam up, thus becoming a > poor > lubricant. I don't know the accuracy of that, but I have read > warnings against overfilling in other places. How much is too > mucH? > I don't want to hassle the shop to bleed off some oil if it's > not too > much. I also don't know the accuracy of the oil level because > it > seems that at that level, the oil level on the dipstick is not > sharp; > instead, it sort of tapers off and becomes spotty. > > I also find black sludge at the bottom few millimeters of the > dipstick, while all the rest of the oil is clear. Never saw > that > combination before. I am told that there was no sludge at the > bottom > of the oil pan. Is this something minor, to be ignored?
A extra cup or even pint is not going to break the bank here for a fre reason. One oil foaming is not the issue it once was long ago and the biggest reason you do not over fill is not because of the foaming causing a lack of lubrication but because if you get a two or three quarts in a small engine you can blow the seals out of the engine. I have seen a few do that but I have never seen a engine damaged from it otherwise and the amount you overfilled is of no concern at all because there is a lot of reserve capacity built in. On a big V8 you need to over fill by 3 or 4 quarts before you start have possible problems with seals generally and a 1 qt over fill of them is of no concern at all.
You have got to be kidding!!! If they were that sensitive to oil level there would be a lot of engines with problems geez! You are trying to scare the guy for no reason. A 1/4 inch over the full mark (give or take) is NOTHING!! A inch or more over full mark in that engine is something to be a bit concerned about but not this amount.
SnoMan wrote: > "Sleeker GT Phwoar" wrote: >>That is far too much. > You have got to be kidding!!! If they were that sensitive to oil level > there would be a lot of engines with problems geez! You are trying to > scare the guy for no reason. A 1/4 inch over the full mark (give or > take) is NOTHING!! A inch or more over full mark in that engine is > something to be a bit concerned about but not this amount.
The whole range from High to Low is what I've designated as 100%. It's about 1.5 inches. So 30% over is about 0.45 inches, which is more than than the acceptable 1/4inch and less than the unacceptable
Ray O wrote: > "Tercel Owner" wrote: >>I got my car back from the shop with fresh oil in the engine. It's >>very transparent on the dipstick, but still discernible. If we >>consider the span from "H" to "L" on the dipstic as 100%, then the >>oil level appears to be 30% over the high mark. >
In the last used engine, I brought the oil level from Low to High with one quart (about 1L). This is different used engine, which my mechanic put in because the 1st one lost oil at well above the rate that he considered acceptable. But I assume it is similar, if not the same design.
I suspected that. The last engine was losing oil, and a plot of oil level with mileage was not a straight line going down. Loss seemed to accelerate as the level approached the Low mark, which means the oil pan gets narrower with depth, at least at the levels measured by the dipstick. I realize that the rate of loss depends on the kind of driving done, but these nonlinearities were repeatable i.e. after topping off the oil to High, the tracked oil loss followed a similar nonlinear loss curve.
That's good to hear. I'm hoping that 30% over the High mark is roughly 0.3L over the High mark, even though I know that the oil pan is wider at the higher levels. Maybe in the worse case, it represents 0.5L, which is still OK by your half-quart figure. (1L is about 1 quart).
It is quite wipable, and quite distinct from the almost transparent new oil. But my mechanic said he checked for sludge on the bottom and found none. I still tend to think of him as frank and forthright, despite past discrepancies (which seem to be within normal human error or variance, the more I think about it).
There's 2 ways I can interpret your description of semi-solid sludge. On one hand, I think you mean that semi-solid sludge that is pliable enough to be wiped away is worse than more solid sludge which sticks like clay. I suspect this is not what you mean. On the other hand, you might mean that semi-solid sludge that is viscous enough to maintain its sludgy consistency on the paper towel is worse than very fluid sludge. This seems to make more sense because it means you're saying sludgier is worse. It also seems to match your last sentence about discoloration on the dipstick. If this is the case, I'm relieved because it does seem to be quite fluid. It would also explain why my mechanic says there is no sludge - because it's actually just old oil.
I must admit though, it's puzzling why the old oil didn't mix with the fresh oil after driving for approximately 7km (about 5 miles), with the oil being pumped up to the head and flowing back down. It is all the more baffling when one considers that the oil showing on the dipstick is the top 1L of oil in the pan. If the capacity is 3L, for example, then there is still 2L in the engine even when the oil is at the Low mark on the dipstick. I would've expected the gunky oil to be at the bottom of the pan (assuming that there is some mysterious reason why it didn't mix).
About engine flush, I think I'll try to achieve the same cleaning effect by changing the oil more frequently than necessary. I've read mixed opinions about engine flush, and it's hard to go wrong by using the more gradual cleaning that comes with frequent oil changes.
Thanks again for your clear explanations.
Tercel Owner
P.S. For this 2nd used engine, my mechanic said he had to change the rear main seals because they leaked. In another thread, someone mentioned that these seals normally last forever, and only leak due to neglect of oil changes. I'm hoping that if this is true, then there are no further problems due to such neglect.
The design should be the same for the same series engine.
A half litre overfilled isn't worth worrying about.
A dipstick will naturally get darker with age, almost like a stain. I wouldn't worry to much about that.
On the other hand,
The thicker the sludge, the bigger the problem. A sludge that is viscous enough to flow can be flushed out with oil changes when the engine is hot. A more solid sludge with the consistency of putty means disassembling the engine to get it out.
If the sludge has the same viscosicty as the oil and just seems like dark oil, that is notmal and nothing to worry about.
Maybe someone added an oil additive or thickening agent. That stuff has the consistency of honey and takes a while to mix with the oil. I'm not a fan of oil additives because good quality motor oil should be enough.
Frequent oil changes is better for your engine than flushes. I consider flushes more of a last-ditch resort than "normal" maintenance.
Front and rear seals will get hard if the engine was in a boneyard for a while. The best way to tell the condition of an engine is to remove the oil pan and inspect the pan and remove the valve cover and inspect the heads. If they are OK, then the seals got hard from sitting dry for a long time.
Actually I was think of a much wider used and much older application of this. Big aircraft engines, particulaly radials, have long had dry sumps and all of the major US bombers in WW2 and a few fighters had dry sumps and large aircraft did until they switch to turbo props or jets but some old piston pounders still flying, like DC3?s, are still dry sump.
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