Acura Repair: 2003 MDX engine oil, oil filler cap, synthetic engine oil

Question
We just purchased a 2003 MDX with 62,500 miles, most of which we think was highway, due to the minimal tire and brake pad wear.  This was a lease vehicle and I'm certain they used regular oil, probably 5w-20 since it was mainly dealer serviced.  There is a considerable (in my view)build up of oil vapor residue on the inside of the oil filler cap.  Is that any cause for concern? Secondly, I have researched the viscosity issue and have found nothing anywhere stating any benefits to 5w-20 oil over the longterm if durability is one's goal. I would hope this Acura engine would go to over 200,000 miles like my 1993 Lexus V8 has and still be in excellent condition.  My plan is to use start using synthetic engine oil (Mobil 1 probably) with this vehicle and my only question is should I use 5w-20, or go to 5w-30 or even 10w-30 during summer? I will appreciate the input of a voice of experience such as yourself on this.  Thanks.  

Answer
Hello John,

Sorry for taking so long to get back to you on this. Do not worry about the vapour residue inside the oil filler cap as that is normal.

As for your oil question, this has been a debated subject for a very long time. In Europe and Asia they use synthetic oil and have been using synthetics for a very long time now. With my high performance Acura engines I only use synthetic oil, preferably Royal Purple 10W-30. I only believe in synthetic oil and the only times I use other then synthetic is after an engine rebuild as the seals need time to expand and since synthetic is very smooth it can and will leak if the seals are not seeded properly. You can use any type 5, 10 or 20 it makes very little difference in your case, heat factures into the equation of what oil to use; Outside temperature, and so on.
A constant 5w-20 is fine DO NOT put 5w-20 then put 10w-30 to top of your engine oil, it will cause damage.

With pure 100% synthetic oil you can drive for 10 to 12 thousand kilometres or 6 to 7 thousand miles before changing the oil. North America is one of the only regions that will not move to synthetic and keep pushing to change your oil every 3 to 4 thousand miles.

When I spoke with some of the Acura engineers from Japan they suggested using synthetic blend. I tell you this because Acura in North America is not in contact with Acura/Honda Japan so they make up their own rules. It does not hurt to use conventional oil but over all Synthetic is the better choice.

I would be very surprised if your Acura Engine does not hold out for anything less then 250,000 miles. Honda/Acura first builds an engine then forms a car around that engine as they are one of the worlds leading engine manufacturers.

If there is anything else don’t hesitate to ask, also if you would like to read an in-depth article on the subject let me know; I will have to find it as I forgot where it is.


Thank you,
Daniel