How do I work out what weighting oil to use?

[DomenEK]

I've done a search on this, but I think I've only confused myself further.

My car has done over 180,000ks, and I'm doing a bit of research into what weight oil I should be using for my next service.

I'm currently using Mobil 1 5W/50, which I've discovered is too thin, and is actually using oil (I last changed it about 5000kms ago, used about maybe 0.5L since then...). I've been thinking of using either Motul 300V Chrono (http://www.motul.com.au/product_line_up/4stroke/4stroke03.html) (10W/40), or Mobil 1 10W/30. But when I spoke to a Honda-specialist service centre and they suggested I use Valvoline Maxlife (http://www.valvoline.com.au/products.cfm?mode=cat3&category=FO&category_title=Petrol%20Motor%20Oil) (20W/50) in a car of my mileage, which has left me confused...

Given that the engine (d16y4) is near-standard, is 180,000+km old, and lives in Brisbane, where the temperature would rarely, if at all, drop below 0 and the hottest it would get would be about 45 in summer, should I be using a 10W/30 (FEO is 10W/30), 10W/40, 20W/50, or what?

Can anybody shed some light on this issue?

[Slow96GSR]

We run thicker oil for really hot days and thinner oil for cold days. Also use what the manufacture says to use.

[aaronng]

When at running temperature of 100C, mobil 1 is actually a 50 weight oil and thicker than 300V 10w-40 and mobil1 10w-30.

Since you have been running 5w-50 in the engine, don't step down to 10w-30 as the thinner oil might not be enough given the clearances in your older engine. I'd say, try a 10w-40 first. Which 10w-40? That's for you to choose. Since you're in brissie where you don't see cold temperatures, then 0w-40 and 5w-40 will perform similarly during cold starts. Why not try Castrol Edge 0w-40?

[DomenEK]

Ok, I might try a 10W/40. But why did the mechanic suggest that the 5W/50 I'm using is too thin (hence why I'm using oil) and suggest I use a 20W/50? I'm still trying to work my head around all this viscosity stuff, lol!

[panda[cRx]]

just use Honda FEO 10w-30, if you still have problems go from there.

[Limbo]

the 5w-50 is considered thin as at cold the oil is very thin but at hot it is thicker.
The first rating is the cold and the second is hot.
So when you park the car it is at cold. THe only reason you change oils is usually when the car starts to burn oils or seems thru the seals overnight. If its not burning or seeping oil, i'd say go for the thinner oil, as honda generally is made with better economy in mind.

You manual will also give you temp ranges for oil viscosities so have a look at that also. If your not burning oil and you don't have any unusual mods or drive like a maniac, try using FEO Honda oil and just check on it. If it burns or runs low, try a thick oil and step your way up. Always check every week to ensure you still have oil in the car. That's the most important thing

[aaronng]

The first number is the viscosity at -18 C though. So at starting temperatures of 10-20C in bris, it's a little higher.

Try a different brand of oil other than Mobil, either 0w-40, 5w-40, 10w-40 and see if you still burn oil. Remember to frequently check and top up your oil if required so that you don't run below the minimum mark.

[bennjamin]

The engineers at honda have already thought out this query...use OEM FEO oil :)