Morning Gents (err Ladies also if any)

Did a lot of searching regarding on this form rearding use of engine oil and the meanings behind the numbers. From my search it seems the # on the oil i.e 5w-30 corresponds to temperature. I am in place where the temp is warm year round. The coolest it gets is 70 degrees and gets over 100.

I went to get my Jag serviced for the first time here (Nigeria) and the guy said he doesn't even sell anything below 10-40. I wanted to get the opinions of other people that live in hot climates regarding oil(s). His major argument was the car would run short of oil before the next service was due. I don't mind adding a liter or 2 here and there. Getting the castrol SAE 5w-30 (4.2L 2010 xf) won't be a problem but I just want to make sure that it won't have an adverse effect due to the more temperate climate.

Thoughts?

 

This link should prove to be beneficial in your decision making - Bob is the Oil Guy just as a side note I use 10w-30w or 10w-40w in both of my cars.

 

The W number is the effective viscosity when "cold". The second number is the effective viscosity at normal engine temperature. This is as compared to single weight reference oils.

ALWAYS use the viscosity recommended by the engine manufacturer. A 40 weight oil is too thick for these engines. Also, the 10W will be too viscous even in Nigeria. I am assuming your Owners Handbook does not permit 10W 40 or you wouldn't be asking. Engines run at coolant temperature which is far hotter than even your ambient temperatures. The oil won't "evaporate" just because the air is hot.

 

Use this link to my page http://jagrepair.com/images/AutoRepa...sb_09_2009.pdf and go to page 94 for Engine oil it has the recommendation for XF 2008.25 – 2010. Using the proper oil is imperative; however, depending on many conditions (your engine health and ambient temperature) thinner oil may not be the right choice just like a too thick of an oil. If you use a 5w-30w oil and you see blue smoke on startup or you have oil consumption issue then you should move up to 10w-30w and see if you have the same issue.

 

There you have it. Use the viscosity indicated in the owner's manual.

 

Thanks a lot for the helpful input guys. Although the oil sales person argument seemed sensible enough, there is a reason car manufacturers state the exact type of oil to be used and I wanted further clarification.

Gus - That manual is pretty sweet. Thanks a bunch for that. Now off to find some oil.

On a side note I find interesting that 2 different Jaguar dealerships in the VA area gave conflicting information about the service intervals. Before I shipped my car I was driving it in northern va and the dealership I took it to said I needed to bring it in every 5 months or 4k miles, whereas another dealership a few miles down the road said I only needed to do the service annually. Thats a steep disparity.

 

I'm not surprised- many people remember the dark days when cars needed and oil change every 3K miles. Despite the advances in engine manufacturing technology and in oil additives, they still cling to that 3K interval despite what the OEM says. I believe your manual specifies a change at a 10K interval or annually

 

OP, not you won't. Just use the recommend oil specifications- whatever the manual says. 5w-30 in this case.

The car has obviously been tested in both cold and hot climates. You will end up hurting the car more going against it's specifications.

 

It seems that having obtained your car in Virginia, you would have a US version of the "vehicle maintenance manual".

As the car is now being operated in Nigeria, you might want to consider the following:

1. consult with knowledgeable locals who are used to the climatic requirements

2. get a peek at the manual that would have accompanied cars shipped in your current local market

3. contemplate the fact that the specification in the book linked by Gus stipulates oil grade but not viscosity

4. remember that in essence, "severe service" is anything other than long highway drives at moderate speeds and moderate temperatures.

5. if you are going to rely on the US manual, read it like a lawyer. the sentence including the phrase "for best fuel economy" is completely misleading. it does not mention "for best wear protection". the real place to look is the temperature/viscosity chart at the bottom of the page. that is intended to help you select a suitable viscosity for the ambient temperature ranges to be encountered in your particular usage.

Notice that thus far, the answers have come from people who reside no further south than Maryland.

Your local guy is more likely to be familiar with your current operating conditions. Besides the fact that the lowest he sells is 10W40, ask him what he recommends. Listen carefully to what he says. Also consider how many oil changes he sees in a day, and how many oil changes the posters have done.

Try browsing around some of the automotive forums based in Australia. Their climate and driving conditions are better match. There are some Australian members here that might chime in. As well, Brutal and Motorcarman are both in Texas.

If there was one right viscosity range to use under all conditions, the oil specification would spell it out in one sentence, in bold, without qualifying clauses and accompanying charts. That is not the case.