5w30 in K20A3?

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When I first changed oil in the Civic SiR (Canadian model) I picked up last year, I put in PP 5w20 High Mileage. They usually have Mobil1 as well, but I think they (Canadian Tire) were out of stock at the time. I'm sure either one is just fine.

The manual states that it can accept 5w30, but should switched back to 5w20 when possible. I've read a number of things about 30 being better for the cams, Honda's only recommending 20 because of CAFE, etc. I saw another thread with UOA/VOA's showing that Mobil1 0w20 actually pushes close to a 30 (I'm not sure if that applies to the H/M formula, though).

Wondering if it's beneficial to just run a 30? Maybe 5w30 in summer and 0w20 or possibly 0w30 winter?
 
Since it is listed as acceptable, and you have data that a 30 is better for cam wear, I'd go 0w-30 all year and agree the 20 is for CAFE.
 
I've got 1 each of M1 5w20, 0w20, and 5w30 for my Accord to use up, bought on sale at different times. After that I'm just going with M1 0w30 year round, since I'm starting to occasionally see it on sale now too. I figure a 0w30 will theoretically be a bit better for severe low or high temps.
 
I had the old K20A3 for 15 years before "upgrading" to a new Corolla. If you've driven both cars you'll know why I used quotes ...‚...‚...‚ I used 0w-30 and 5w-30 year round and had a horrible ticking at about 50k miles. Exhaust cam lobes gone. It was bad metallurgy from factory, is what I heard. Replaced exhaust cam, ran everything from 0w-20 to 5w-40 for the next 150k miles. No cam issues. Just bad seatbelt sensors, brake calipers seizing, and idler pulley bearing.

So, in my opinion, use whatever in it. The crappy cams are due to crappy cams, not 5w-20.
 
Honda K series engines typically like a viscosity on the lower end of the scale (5-20, 0-20). The slightly thinner oil helps the spool valve actuate the VTEC system a bit faster. But, the real issues are cavitation with the oil pump/pick up(above 8500 rpm) and oil starvation to the last cam tower at sustained high RPM--the thinner oils help increase the flow/volume to a certain extent.

Since our poster has the K20A3, he doesn't have to worry about the spool valve or vtec, or turning the engine much above 7K--hence, 0-30 oil would be an excellent choice.
 
Originally Posted by jeff8407
Honda K series engines typically like a viscosity on the lower end of the scale (5-20, 0-20). The slightly thinner oil helps the spool valve actuate the VTEC system a bit faster. But, the real issues are cavitation with the oil pump/pick up(above 8500 rpm) and oil starvation to the last cam tower at sustained high RPM--the thinner oils help increase the flow/volume to a certain extent.

Since our poster has the K20A3, he doesn't have to worry about the spool valve or vtec, or turning the engine much above 7K--hence, 0-30 oil would be an excellent choice.


Looks like the European oil specs clearly state NOT to use a 20w, at least on the 06-11 high revving K series

Euro Oil Spec
 
Originally Posted by jeff8407
Honda K series engines typically like a viscosity on the lower end of the scale (5-20, 0-20). The slightly thinner oil helps the spool valve actuate the VTEC system a bit faster. But, the real issues are cavitation with the oil pump/pick up(above 8500 rpm) and oil starvation to the last cam tower at sustained high RPM--the thinner oils help increase the flow/volume to a certain extent.

Since our poster has the K20A3, he doesn't have to worry about the spool valve or vtec, or turning the engine much above 7K--hence, 0-30 oil would be an excellent choice.

I'm not familiar with the exact mechanisms of VTEC, but the A3 does have a sort of VTEC "light" that only applies VVT to the intake valves and not the exhaust. There's no distinct switchover in the rev range.
 
Too late to edit. Did some light reading on the i-VTEC system in my car. It only applies VVT to the intake valves, but it is still an oil-driven mechanism.

So, I'm thinking I'll stick with 20, but I'll switch to one on the heavier side. Suggestions? I'd prefer to stick with a high mileage formula if possible.

This thread shows a VOA suggesting that M1 makes a thick 20, but that was over 15 years ago (!!!).
 
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Honda runs best on xx-30 grades. According to my experience with honda engines.

And Honda EU spec is xx-30 for cars. 10w-30 for motorcykle and marine engines.
 
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