Synthetic 5W-40 vs. 10W-60

[Falcon_LS]

I live in Kuwait, and own a 2000 Mitsu Pajero/Montero (3.0L v6) with 246,000 km (153,750 miles) on the clock. Because of the climate conditions in the Middle East, Mitsubishi's recommended viscosity is 15W-40 for normal conditions and 20W-50 for severe operation. Since my Pajero was maintained by the dealer, 20W-50 was always used until I switched to Motorcraft Synthetic Blend 10W-30 at one point, which meets the ILSAC GF-4 specification, but I'm now back to 20W-50 again (BP Visco 2000 meeting API SJ/CF specs to be precise about what I'm using). I realise 5W-30 was the recommended viscosity for this engine in the States, but climate conditions in places like Australia and the Middle East call for thicker oil and are recommended by the manufacturer as such.

That said, I've cleaned the internals of my engine with Auto-Rx and the engine internals are pretty clean. Since they are clean, with low oil consumption, I'm considering a switch to full synthetic - mainly Castrol Edge or possibly the slightly cheaper BP Visco 5000. Then again, BP owns Castrol and I'd imagine the formula itself is very similar. As they are synthetic, I can extend my oil changes to at least 15,000 km (9,375 miles) over the standard 5,000 km (3,000 miles) and they obviously perform much better than conventional. Most oils meet API specifications here, unlike places like the UK and the rest of Europe, where oils must meet ACEA specs, which are much tougher and hence conventional oil is good for 10,000 miles. Then again, climate conditions in Europe vary quite a bit!

Now there are 2 choices with synthetic motor oils I am considering, both of which I believe are a Group IV: Castrol Edge 5W-40 and Castrol Edge Sport 10W-60. Although the engine is as clean as a whistle, it is still a high mileage motor and I'm naturally learning towards the thicker Castrol Edge 10W-60. I realise this is 10W over the manufacturer's suggested CST when hot, but again the mileage is high. That said, would 10W-60 be a decent choice, or would I be better off sticking with the 5W-40? The Edge 5W-40 meets API SL/CF and ACEA A3/B3/B4. It is also VW 502 00, VW 505 00, MB 229.3, BMW Longlife-98 approved. The Edge 10W-60, on the other hand, only meets API SL/CF and ACEA A3/B3/B4 specifications with no approvals from VW, MB of BMW. Any assistance will be muchly appreciated. Thank you.

 

[SuperDave456]

I would go with the 5w-40.
It will be thick enough to protect the engine in those tempatures, yet flow better than the 10w-60 thereby lubricating more efficiently. Since you have run an Auto RX cycle we know things are clean and the oil can flow as the designers of the engine intended it to.

The Mideast has similar tempatures to the United States Midwest, Arizona and New Mexico. I would feel comfortable driving your Montero with a 10-w30, however a 5w40 will work exceptionally well also.

The only thing I would do is be sure to change out your air filter regularly. The dust over there is nothing like we have in the US and that has got to kill engines.

 

[Falcon_LS]

Thanks very much, Dave! I think the 5W-40 also seems to be a better quality oil, as it seems to be approved by German manufacturers.

I usually blow my air filter out with compressed air every second fill up, and replace it at the 10,000 km (6,000 mile) mark. It's cheap insurance against future problems.

That said, I read somewhere that oils meeting the MB229.3 specification are good for 20,000 km or 12,500 miles. Is there any truth to this? Both Edge products are marketed as being 'good' for 15,000 km (9,375 miles), but it would be good to get an extra 5,000 km or 3,000 miles out of them.

 

[oilboy123]

I believe that if you are using a good synthetic oil that you don't need to go higher than a 40wt oil. 50 and 60 wt are pretty thick oils........

Try the 40 wt and see how it goes. Do a UOA on one of your changes. Be careful blowing out an air filter that is not made for that. It can compromise the filtering ability. It could create small holes that were not there to begin with.

Amsoil air filters are the only one I know of that allow you to blow or vacuum them out.

 

[d00df00d]

+1, 5w-40 all the way. No need for a 10w-60.

In the hottest parts of your engine, Edge 5w-40 will probably be almost as thick as your old 20w-50 anyway. Edge 10w-60 would be way thicker than necessary.

 

[Falcon_LS]

Thank again for the useful info! We do not have UOA facilities locally, but I can get one done in the UK...which I have done before for another vehicle.

The OEM air filter on Mitsubishi's are actually made of pretty tough material. The inner side actually has a tough cotton-like coating, which prevents any holes, etc. from forming...then again I replace it every 6,000 miles instead of the recommended 15,000.

 

[hate2work]

Maybe you could find a 10W-50 syn oil that would be a good compromise. I don't know what oils are available to you over there, so I can't make a recommendation.

 

[Doug Hillary]

Hi,
Falcon_LS - I had three V6 Pajeros (two autos/one manual) starting from 1989 and did about 100kkms in each. They were all fed Castrol R 10W-60 - it was a trouble free choice with zero consumption in each. I always carried out 10kkms OCIs

The V6 engine is a dream (roller rockers etc) and the thermostatically controlled oil cooler adds to the lubricant's durability as well

 

[jlomon]

Mobil 1 makes a 5w50 synthetic.