Engine Oil Question And Link To Comprehensive Article

[harrylime]

I'm thinking about an engine oil change, due to time interval, rather than mileage. The oil looks like new. However, I am considering using Mobil 1 0w40, rather than the 5w40 that seems to be the standard. My reason is that although the viscosity is the same as higher temperatures, it is lower at lower temperatures, which may help with mpg and reduce wear in cold temperatures, especially for short journeys. Has anyone used this oil, and is anyone aware of any reason why I should not deviate from the standard?

I know the engine is likely to outlast me in either event, and I hesitate to deviate from manufacturers' recommendations, but I don't even know whether Mobil 1 0w40 was even available when the LS was developed. Common sense tells me that thinner oil when cold must be better?

The following link is a piece written on the American Lexus club forum. There is some interesting stuff, but I lost interest well before the end and it does not really answer my question: I am likely to use either the Mobil 1 or Castrol magnatec

http://www.clublexus.com/forums/performance-and-maintenance/644401-facts-about-oil-and-what-grade-to-choose.html

[cruisermark]

for 3 years with my mark 3 and 2 years with my mark 4 I used Castrol edge 0w-30 without any problems.

[Cotswold Pete]

Having also wondered about 0w30 and the like, and having read a fair chunk of that article, i would say in the UK in the main it matters not.

However if you are going to move to somewhere with a Continental climate (USA, Mongolia, Romania etc) then the oil will make a slight difference.

However as I understand it, the Lexus engine was not meant to be thrashed when cold (or hot for that matter), so dealing with changes in stiction due to rapidly fluctuating oil and cylinder temperatures in likely to be a non-issue.

Brand new modern engines will have tighter tolerances, but wear in first 10K miles usually does not get that much worse if you do regular oil change and do not thrash the thing from cold.

But I would agree with the chap that oil is not simple if you have supercars and a need to take them to the limit, and they need to extract every last drop of horsepower out of the petrol to make it worth while having a car that cost that much and does nought to 60 in the time it takes to turn on the radio!!

[harrylime]

The manual has a range of recommendations, starting at 5w30. No mention of 0w30 but it may not have been available back then. I would imagine it makes little difference generally, but would think that starting and initial running is easier when cold, and therefore more efficient.

[keybasher2]

I recently changed the oil to Mobil 1 esp 5w/30 and noticed the car takes another mile or so to get to temperature (old oil about 3k old) Not sure its a good or bad thing,I`m thinking maybe the engine bits are a bit more slippery and run cooler,my other thought is that lots of engine wear takes place during warm-up so maybe a bad thing !! (cars done 164k) Guy at Europarts says they never put Mobil 1 on shelves as it always gets nicked ! indication of good oil ? :shifty:

[harrylime]

Simon, that is interesting (especially as my car is also a 1999). Someone may correct me on this but does that not indicate more efficient running? Less friction, less mechanical energy converted to heat. Heat is wasted energy? The only disadvantage may be more time for the heater to warm through?

What is your mpg like? I can't get mine over 23 mpg , even on a run.

[keybasher2]

I`m getting approx 19mpg on my 3.5 mile journey to and from work (lots of stop start) Not calculated on a run but will be doing a 200 mile jaunt this weekend,will let you know the outcome.

[bigjap]

i have used Mobil 1 0/40 in my car for 2 yrs its been ok

[keybasher2]

Returned 30 mpg average on computer over the 200+ miles with 95% motorway !! Well chuffed