LowiePete
Well-Known Member
Hello Folks,
This topic is a subject that I've long been researching an answer to, particularly as
some of the "popular" marques are seemingly no longer manufactured and are
fetching quite spectacular and stupid prices. The price of oil filters is going so far
north it's becoming a cheque-book sport. For what is nominally a simple service
item, that's just daft. The whole point of these parts is that they are changed
properly and frequently.
So, as the owner of a 2L petrol turbo Renault I was rather surprised to find that
the oil filters for the F4R engine have more or less identical dimensions as those
fitted to the smaller, historical C1J engine. I've broached this subject here before,
only to find objections because of presumed "oil pressure loss". To be honest, I
didn't buy those arguments then and, having done more research since, I certainly
don't buy them now.
If it means that I can replace the oil filter at frequencies of at least twice or more by
using one that has been developed for the modern era, that is for engines (and oil)
developed long after the C1J went out of production, then so be it. The idea that we
be tempted to "stretch" the life of filters that were previously specified because of
cost or rarity just becomes daft. So, with this overlap in mind, what should we look for?
Well, it's very simple, although finding the evidence for this simplicity has not been
at all easy. The first bit of research is in oil pressure measurements. The absolute
critical measurement is that the by-pass valve is not forced to open and let through
unfiltered oil until it's absolutely necessary. Next comes the flow statistics, that is
the filter not interfering with the oil pressure on the exit side. That can fairly easily be
answered by the physical dimensions. In other words, if the enclosure dimensions are
similar, then the flow will also be well within tolerances. Indeed, it could be argued
that flow, at a non-diminishing pressure, will be as good or better with modern filters.
So, it comes down to getting accurate statistics regarding oil pressures at critical
moments and making comparisons. Trying to track these down has not been an easy
job. They are, thankfully, available in tech publications from Renault. For the C1J it
came down to researching period publications. For the F4R they're found deep in the
Dialogys system. So, to the figures...
C1J Turbo
Revs @ 750 rpm (idle) 1.3 bar
Revs @ 4,000 rpm (turbo active) 3.2 bar
F4R Turbo
Revs @ idle 0.4 bar
Revs @ 4,000 rpm 2 ~ 4 bar
What the figures show is that the tolerances of the 8200 768 913 oil filter for the
later Renault engine will happily cope with the C1J engine. So that should make the
market for paying well over the odds collapse. I've discussed this at length with Karl,
my Renault mechanic of many years, and it's quite clear that he won't be screwing-up
his nose at me for substituting them. I'm not inclined to ignore his advices at the
best of times.
Like me, he's far happier that the filter gets a regular change, rather than sticking to
what is likely to be old technology at what is becoming stupid pricing. This especially
as the specs of the oil have not stood still in the intervening years either.
Regards,
Steve
This topic is a subject that I've long been researching an answer to, particularly as
some of the "popular" marques are seemingly no longer manufactured and are
fetching quite spectacular and stupid prices. The price of oil filters is going so far
north it's becoming a cheque-book sport. For what is nominally a simple service
item, that's just daft. The whole point of these parts is that they are changed
properly and frequently.
So, as the owner of a 2L petrol turbo Renault I was rather surprised to find that
the oil filters for the F4R engine have more or less identical dimensions as those
fitted to the smaller, historical C1J engine. I've broached this subject here before,
only to find objections because of presumed "oil pressure loss". To be honest, I
didn't buy those arguments then and, having done more research since, I certainly
don't buy them now.
If it means that I can replace the oil filter at frequencies of at least twice or more by
using one that has been developed for the modern era, that is for engines (and oil)
developed long after the C1J went out of production, then so be it. The idea that we
be tempted to "stretch" the life of filters that were previously specified because of
cost or rarity just becomes daft. So, with this overlap in mind, what should we look for?
Well, it's very simple, although finding the evidence for this simplicity has not been
at all easy. The first bit of research is in oil pressure measurements. The absolute
critical measurement is that the by-pass valve is not forced to open and let through
unfiltered oil until it's absolutely necessary. Next comes the flow statistics, that is
the filter not interfering with the oil pressure on the exit side. That can fairly easily be
answered by the physical dimensions. In other words, if the enclosure dimensions are
similar, then the flow will also be well within tolerances. Indeed, it could be argued
that flow, at a non-diminishing pressure, will be as good or better with modern filters.
So, it comes down to getting accurate statistics regarding oil pressures at critical
moments and making comparisons. Trying to track these down has not been an easy
job. They are, thankfully, available in tech publications from Renault. For the C1J it
came down to researching period publications. For the F4R they're found deep in the
Dialogys system. So, to the figures...
C1J Turbo
Revs @ 750 rpm (idle) 1.3 bar
Revs @ 4,000 rpm (turbo active) 3.2 bar
F4R Turbo
Revs @ idle 0.4 bar
Revs @ 4,000 rpm 2 ~ 4 bar
What the figures show is that the tolerances of the 8200 768 913 oil filter for the
later Renault engine will happily cope with the C1J engine. So that should make the
market for paying well over the odds collapse. I've discussed this at length with Karl,
my Renault mechanic of many years, and it's quite clear that he won't be screwing-up
his nose at me for substituting them. I'm not inclined to ignore his advices at the
best of times.
Like me, he's far happier that the filter gets a regular change, rather than sticking to
what is likely to be old technology at what is becoming stupid pricing. This especially
as the specs of the oil have not stood still in the intervening years either.
Regards,
Steve
