Hey everybody I need help. What is the best oil for my 2004 M45. The dealer uses reg oil but I think with this kind of motor you should use full synthetic like castro 10-30. What do you all think.

Thanks Dave

altec, today’s major brands “regular” motor oils are quite good and should do well in your Infiniti if you drive in moderate climate conditions. However, if your climate conditions are extreme, a semi-synthetic or full synthetic motor oil will better protect your car.

I live in Arizona, a state with extreme climate conditions. We experience great heat in summer and very cold winters. During the monsoon season, we have very strong dust storms. Thus, I use full synthetic motor oil all year long.

Over the years, I have purchased various brands of synthetic and semi-synthetic motor oils for all of my high performance cars. Doing so I have not found a significant difference in them. As a result, I buy a major brand full synthetic oil based solely on cost; I buy the one whose cost is the least at the time an oil change is needed.

To date, I have never had an engine problem of any kind.

Good advice.

In general, doing the oil changes on time, with a good dino oil or a synthetic, is more important than the specific brand you use per se. However, there are differences between brands - some are indeed better, but if the oil change is often enough, these are not critical at all.

Most oils are completely "done" by about 4000 to 5000 miles and no longer protecting your engine, so changing at a more frequent interval is better - many people find the 3000 mile to be the convenient point. I like to use the 3750 mile mark as my change point because it is halfway between the mftr procedures for other things, so I use a synthetic to make sure that the slight extra miles are not an issue. By the way, people who do "extended" oil changes are simply asking for trouble - oil costs are low enough that this should not be a normal practice.

In the past, our resident oil expert (chemist, does it for a living/profession) who is not participating in this forum much anymore unfortunately, recommended some good oils, and I have picked out the ones that I have found to work for me and are generally easily available.

Good dino oils:

1. Castrol GTX 5W-30 and 10W-30.2. Chevron Supreme 5W-30 and 10W-30.

Good synthetic oils:

1. Valvoline Full synthetic 5W-30 and 10W-30.2. Mobil 1 Synthetic 5W-30, 10W-30 and 0W-40.

The Mobil 1 0W-40 is an excellent wide-temperature range oil (without sacrificing the detergent levels and overall quality) for just about anywhere in the country at any times of the year - short of extended sub-zero temps (like winter in Minnesota or Canada). This has become my "standard" oil for both my cars - even here in mild Northern California.

When I have the dealer do the oil change at the 7500 mile intervals, I take my own oil in with me (buy it from a local Kragen) and the dealer gives me a discount on the overall maintenance work ... about $5 to $10 worth, as I recall.

Two other notes:

First, use a good dino for the first 7500 to 10000 miles. This is needed to let the pistons and rings settle in. Switch to synthetic after that. Yeah, I know some car mftrs and models (Corvette as an example, I believe) have synthetic fills at the factory, but I think that this is not a good practice.

Second, on new cars, many early oil changes are very helpful to prolong the life of the engine. Mercedes Benz, for example, recommends on some models, an oil and filter change after a few hundred miles! If you do a search for a post here on "oil consumption", you will see what I did for my car, and why, I believe, it has resulted in one of the lowest oil consumption issue engines in the 2003/4 M45 years!

Regards,

Z