Here's the latest word on 5w20 vs 0w30 viscosity in a 2003 Honda
Accord EX. i am sure that many of you have wondered and read about why
certain companies like Honda and Ford are using 5w20 insead of say
5w30 or 5w40 as in European cars. Contrary to the popular belief that
Honda used 5w20 to meet CAFE requirements it is mostly due to engine
tolerances. I have recently opened the Accord engine cover to examine
the valve clearance as the valves started to get a bit noisy. To my
surprise I have noticed slight groves and pitting in the cam lobes. A
mechanis from the US has asked me if I were using a wrong oil. I asked
what is wrong oil. He asked whether I used a higher viscosity oil
higher than 5w20. I said I used Amsoil 0w30. What he claimed is that
the camshafts did not get adequate volume of oil and the fact that
they are the furthest in oil circuit, they got less oil than they
should have due to lower flow of oil. This is theoretically possible,
but I am not sure that pitting of the lobe material is due to reduced
lubication. To me it looks like poor quality of material or poor
quality control during manufacturing of the camshafts. The vehicle
still does not burn more oil than it did when it was much newer i.e.
0.5l per 10,000Km. I am now going to switch to synthetic 5w20 in hope
that the cams and the followers will last until 500,000Km. Does anyone
have similar experience with their camshafts?
You're talking through your hat, Mr. Metric Slave.
Below is one of the most critical clearances in any engine, one that has a
lot to do with oil pressure and consumption.
1991 Integra, 5W-30 oil specified.
Crank bearing clearance: .0007"-.0017", max .0020"
2003 RSX, 5W-20 oil specified.
Crank bearing clearance: .0007"-.0016", max .0020".
All the other relevant clearances I can find in my manuals are similarly
identical. 5W-20 is specified for CAFE reasons and no other.
And just for fun I looked up the same clearance on a 1952 Ford OHV six.
.0005"-.0021". Whaddya know. You suppose they were using 5W-20 in 1952?
Heh heh heh... It's amazing on how specs for machanical components have
hardly changed over the years ain't it?
The biggest issue with camshaft wear as far as I can tell is the
reformulation of engine oils that remove direct contact "cushions."
This is an issue facing a lot of owners of older cars and is yet another
guv'ment mandate. (I can't speak for youse Canadians though).
To the best of my knowledge, only oils that meet Caterpillar's diesel
standard still have these ingredients. (Caterpillar uses Shell Rotella
from what I understand).
But, I'm not going to lose any sleep over this nonsense. I have a few
extra camshafts (and lifter sets) to keep me runnin' for a few years...
There is some evidence that organo-moly offers the same "wear pad"
protection that ZDDP used to provide. The API has not yet conducted
tests to definitively confirm this, though.
It's my understanding that engines with excessive cam-train wear rates
are performance engines with flat tappets, high spring rates and high-
lift cams. Your average road car has sufficiently developed metallurgy
that cam-train wear is not an issue even in the absence of ZDDP.
The API has stated on the record that older engines exhibit no excessive
wear with low-ZDDP GF-4 oils.
ZDDP is not the be-all-and-end-all of wear protection.
I share the same assessment and hope that your, er, I'm right.
And then there was that issue of valve seats being a problem when lead
was removed from gas. That has generally not proven to be the case with
Studebakers. So far so good..
Again, from extensive reading, it's my impression that valve seat recession
in the absence of TEL occurs primarily in situations that contain some or
all of the following:
high spring rates;
high cam lift.
I'm seeing many reports that most standard pre-unleaded road-going engines
are getting by just fine without lead protection. Mind you, most of the
vehicles containing such engines are now considered "classics" and are
generally driven in a very sympathetic manner.
ZDDP was drastically lowered in gasoline motor oils in order to meet
government-imposed warranty requirements on catalytic converter life.
It happened around 1995, with the introduction of
You might have a point here. I also called Amsoil to discuss the
difference between 2 oils in the engine and the situation. They have
also firmly suggested not to switch to 5w20 whether it be Amsoil's or
Honda's oil as it will accelerate the wear of other components which
are currently functioning properly. It appears that a lot of people
don't like the 5w20 oil. It would be interesting to find out if there
are other higher milage vehicles out there that have used 5w20
I talked to at least a dozen oil experts, some who have Ferrary
vehicles for a long time and don't follow factory suggestions. Most
have convinced me that 0w30 synthetic is the best motor oil for my
application. The best advice I got was from a man who owns a late 80s
non-diesel mercedes with almost 1 million kilometers without any
repairs. His suggestion is to not rev the engine beyond 4000RPM any
more. Try to accelerate as slowly as possible without interfeering
with the traffic behind. Use high quality 0w30 or 5w30 synthetic.
Change it at 10,000 mile (16,000Km) intervals including the oil
filter. Before filling with fresh synthetic oil, clean the engine with
cheapest fresh oil (doesn't need to be synthetic) for approximately 15
minutes or longer if in winter. NEVER use petroleum based engine
flushes. Flush the transmission on every change interval that I follow
(for me it's every 50,000KM) i.e. drain, fill, drive 3 times. Make
sure the tires are always properly inflated i.e. check every week. The
idea of the latter suggestions is to reduce the load on the engine as
much as possible. Lastly, take a sample of the oil during the drain
and send to lab for analysis. He did this every 50,000km. I've never
done it, but I will do this at my next oil change. I am kind of
curious as to what the report will show. Some people I talked were
truckers. Alot of them use Amsoil. Some are obsessed with oil. They
have onboard oil centrifuge-like gadgets that act as oil refineries
that allow for driving up to 100,000Km before replacing the oil.
Thank you all for your suggestions.
The engines in Europe have the same clearances as the US engines and they
don't require 5W20 oil. Your mechanic was BSing you. I had the same sort of
experience with Ford. I complained about a start-up noise and the first
question was "Are you using 5W20 Oil?" I was, so they couldn't use that as
an excuse. A friend had a Ford that smoked slightly at start-up (probably
leaky valve seal). The dealer told him to switch to 15W40! It didn't cause
any problems, but it didn't fix anything either.
Using 5W30 oil instead of 5W20 oil can't be a problem. Either oil is thicker
at a cold start-up than at operating temperature. If the oil passages and
clearances are so critical that the difference between 5W20 and 5W30 is
significant for a warmed up engine, there will be major lubrication issues
during cold starts.
I'd say the wear you described was not unusual for an engine with 340,000
km, particularly if you have been using second rate oil and not changing it
at the recommended intervals. I think it is not necessary to change to 5W20
oil. If the rest of your engine is worn, the bearing clearances are likely
greater than when new, and the 5W20 oil will leak out of the bearings
faster, negating any advantages you think you might get because the 5W20
Nonsense. That same engine family is sold in other parts of the world
with much thicker oil specified. Somehow I also don't think that the
Acura TSX high output version of the Accord 4 cylinder is built to
"looser tolerances" than the Honda version, yet the Acura calls for 5W-30.
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