RV8 oil consumption
Discussion
I have had my RV8 4.6 rebuilt, and have been running it in to the tune of 2500 miles (spec in profile).
It turned out the rear main seal had been nicked when installed, and was leaking, so have had it sorted, but the engine still seems to be using oil...
I am trying to measure consumption over miles - but was wondering what I *should* be expecting..?
In an *average* engine how many miles should I expect the engine to lose say 1 litre of oil..?
cheers,
Dom
It turned out the rear main seal had been nicked when installed, and was leaking, so have had it sorted, but the engine still seems to be using oil...
I am trying to measure consumption over miles - but was wondering what I *should* be expecting..?
In an *average* engine how many miles should I expect the engine to lose say 1 litre of oil..?
cheers,
Dom
Thee is no 'set' degree of consumption. There is only excessive.
It is often the case that a newly rebuilt engine will use a lot of oil, using more oil after just having been rebuilt than after it has got a few cycles under its belt.
In the long term, pumping burnt oil down the exhaust will nacker the cats and can cause excessive deposits in the combustion chambers, on the valves and along the route out.
But that, of course, doesn't answer you question.
I'd suggest that if the plugs aren't getting oiled up then run with the degree of consumption you are getting at the moment and then worry if it doesn't drop.
Quotes that I've heard is that between 500 and 1000 miles per litre is around the norm. I wouldn't get too worried if you are running a bit more than that at the moment but I would expect it to settle within those limits eventually.
Oil consumption varies on factors other than gaps. Frequent stop-starts, where the engine isn't thoroughly warm, can increase it as can harsh acceleration and sudden lifting off. Long runs at constant high speeds should make it fall. A tuned engine might well have more generous gaps as can one where higher tempratures have been planned for.
If consumption is rather excessive and you feel you can't live with it then it must be investigated. It is my experience that excessive oil consumption, especially if it suddenly increases, is more likely to be valve guide wear.
Whatever the cause, it is unlikely to be a fault in all eight pots so inspect your plugs carefully. If they are all more or less the same then I'd suggest things are more or less ok. Having one that comes out covered in tar is always a bad sign.
I did one journey from Brighton back to my home in Greenwhich in the 60s at a tremendous 30mpp of 20/50 Duckhams (very expensive for the time). That was caused by a newly liberated little end that decided to experiment with horizontal movement rather than merely up and down. There were four vertical grooves in no. 1 pot. They were barely visible. I found it difficult to believe that so much oil could have got along them in so short a time.
It is often the case that a newly rebuilt engine will use a lot of oil, using more oil after just having been rebuilt than after it has got a few cycles under its belt.
In the long term, pumping burnt oil down the exhaust will nacker the cats and can cause excessive deposits in the combustion chambers, on the valves and along the route out.
But that, of course, doesn't answer you question.
I'd suggest that if the plugs aren't getting oiled up then run with the degree of consumption you are getting at the moment and then worry if it doesn't drop.
Quotes that I've heard is that between 500 and 1000 miles per litre is around the norm. I wouldn't get too worried if you are running a bit more than that at the moment but I would expect it to settle within those limits eventually.
Oil consumption varies on factors other than gaps. Frequent stop-starts, where the engine isn't thoroughly warm, can increase it as can harsh acceleration and sudden lifting off. Long runs at constant high speeds should make it fall. A tuned engine might well have more generous gaps as can one where higher tempratures have been planned for.
If consumption is rather excessive and you feel you can't live with it then it must be investigated. It is my experience that excessive oil consumption, especially if it suddenly increases, is more likely to be valve guide wear.
Whatever the cause, it is unlikely to be a fault in all eight pots so inspect your plugs carefully. If they are all more or less the same then I'd suggest things are more or less ok. Having one that comes out covered in tar is always a bad sign.
I did one journey from Brighton back to my home in Greenwhich in the 60s at a tremendous 30mpp of 20/50 Duckhams (very expensive for the time). That was caused by a newly liberated little end that decided to experiment with horizontal movement rather than merely up and down. There were four vertical grooves in no. 1 pot. They were barely visible. I found it difficult to believe that so much oil could have got along them in so short a time.
My 390 (John Eales blueprinted engine) uses around 1 litre per 500 miles or thereabouts, this has been the same from new. When it's on the track and everything expands to fill the gaps (as it was built to do) then the oil consumption is negligible.
Check the oil you are using, the RV8 was originally designed to run with 20W/50 multigrade oil that was available at the time, if you are using a thinner modern oil then the consumption will be worse.
Unless you have cats then don't worry about it if it is not excessive, you will get a nice brown patina around the back of the car that does wash off with shampoo and water.
Russ Wood
Check the oil you are using, the RV8 was originally designed to run with 20W/50 multigrade oil that was available at the time, if you are using a thinner modern oil then the consumption will be worse.
Unless you have cats then don't worry about it if it is not excessive, you will get a nice brown patina around the back of the car that does wash off with shampoo and water.
Russ Wood
Early 390s...of the John Eales build type, were run from new on Century Supreme synthetic oil and used around 1 litre every two tank fulls of fuel. The oil never allowed the rings to bed in.
It maybe your high oil use beyound the running in period is due to running in on the wrong oil, with the same consequenses as above, or running oil that is too thin when cold??
It maybe your high oil use beyound the running in period is due to running in on the wrong oil, with the same consequenses as above, or running oil that is too thin when cold??
My current 400 Chim oil use is negligible on Mobil1 15/50.
My previous 500 was run on Mobile Helix 5/40 and used a litre every 500 miles or so.
There is a school of thought that thinner oils in the RV8 are a waste of time and don't get pulled up the cylinder bores like the treacly oils of yesteryear. I'm sure some of the technical guys on here will explain.
My previous 500 was run on Mobile Helix 5/40 and used a litre every 500 miles or so.
There is a school of thought that thinner oils in the RV8 are a waste of time and don't get pulled up the cylinder bores like the treacly oils of yesteryear. I'm sure some of the technical guys on here will explain.
Experience from the 500s isn't really applicable since they have shorter pistons and fewer rings. I suspect the same is true of most of the exotic engines. A 4.6 with standard pistons would have a full set of rings and low oil consumption, around 1L per 5000 miles once it's run in properly.
They have the same number of rings 
? Just different sizes ala 3.9/4.2 vs 4.0/4.6?
I am of the opinion the rings bed in PDQ, like first 100 miles, running in the bearings takes longer and shouldn't be confused? Starting first time should have some aggression in my mind to force the rings out. There are also different style rings and depending how they were fitted (care taken ..) can make a lot of difference to the results you get. File fit / fettled bevels / quality / off the shelf dumped in... without even going into more exclusive versions
? Just different sizes ala 3.9/4.2 vs 4.0/4.6?I am of the opinion the rings bed in PDQ, like first 100 miles, running in the bearings takes longer and shouldn't be confused? Starting first time should have some aggression in my mind to force the rings out. There are also different style rings and depending how they were fitted (care taken ..) can make a lot of difference to the results you get. File fit / fettled bevels / quality / off the shelf dumped in... without even going into more exclusive versions
TVR_owner said:
Early 390s...of the John Eales build type, were run from new on Century Supreme synthetic oil and used around 1 litre every two tank fulls of fuel. The oil never allowed the rings to bed in.
It maybe your high oil use beyound the running in period is due to running in on the wrong oil, with the same consequenses as above, or running oil that is too thin when cold??
Mine didn't have the Century oils in it - I think that came later (but yours was earlier than mine). Didn't Century oils have a scheme where you could send an oil sample in every time it was changed so Century could tell you what the state of wear of the engine was?It maybe your high oil use beyound the running in period is due to running in on the wrong oil, with the same consequenses as above, or running oil that is too thin when cold??
Russ
C O Jones said:
TVR_owner said:
Early 390s...of the John Eales build type, were run from new on Century Supreme synthetic oil and used around 1 litre every two tank fulls of fuel. The oil never allowed the rings to bed in.
It maybe your high oil use beyound the running in period is due to running in on the wrong oil, with the same consequenses as above, or running oil that is too thin when cold??
Mine didn't have the Century oils in it - I think that came later (but yours was earlier than mine). Didn't Century oils have a scheme where you could send an oil sample in every time it was changed so Century could tell you what the state of wear of the engine was?It maybe your high oil use beyound the running in period is due to running in on the wrong oil, with the same consequenses as above, or running oil that is too thin when cold??
Russ
GreenV8S said:
spend said:
They have the same number of rings ? Just different sizes ala 3.9/4.2 vs 4.0/4.6?
As I understand it, the 500s use shorter pistons which have fewer rings, hence the 500s routinely use about five times as much oil as the 400, 450 etc.? Just different sizes ala 3.9/4.2 vs 4.0/4.6?spend said:
GreenV8S said:
spend said:
They have the same number of rings ? Just different sizes ala 3.9/4.2 vs 4.0/4.6?
As I understand it, the 500s use shorter pistons which have fewer rings, hence the 500s routinely use about five times as much oil as the 400, 450 etc.? Just different sizes ala 3.9/4.2 vs 4.0/4.6?Englishman said:
Difficult to say exactly how much as depends on usage but definitely check every month or 1000 miles max and expect to add at least a litre.
That's completely typical oil consumption for a 500, but massively more than normal for a healthy 400 or 450. The 500s use substantially more oil, I'm told it's because of the missing oil control ring.Quinny said:
A RV8 500 has exactly the same rings as any other varient with 94mm bore..
Andy, just to be clear there are 2 ring packs AFIK, the thickness of the rings (groove size) is different between 3.9 and 4.0, 500's happen to use the 3.9 pistons ring specs (as does the 4.2/4.3) and the 4.6 the same as the 4.0.Hmmm
There seems to be quite a large discrepancy between those putting virtually none in, and those where 1l lasts about 500m...
Mine is obviously still running-in, but by estimation I am seeing 1l at about 300-500miles...
I will monitor this, and see if that estimate is right...
Why does the RV8 engine use so much oil..?!
Dom
There seems to be quite a large discrepancy between those putting virtually none in, and those where 1l lasts about 500m...
Mine is obviously still running-in, but by estimation I am seeing 1l at about 300-500miles...
I will monitor this, and see if that estimate is right...
Why does the RV8 engine use so much oil..?!
Dom
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