I did a quick review of this thread and deducted that those of using the 10/30 are in Florida, Texas and Arizona. - Warmer areas where we don't need the thinner oil for a cold start and a thicker viscosity at start up is preferred, at least that's my reason.

 

I put less than 5000 miles a year and change my twice a year, fall and spring and use Pennzoil Platinum synthetic or Mobil One 5W-30 and Wix filter.Since I change it myself I spend the extra on the synthetic.If I did drive more miles I would still change the filters twice a year and run the oil up to 7.5-10K.I have been told that synthetic doesn't break down as quick as dino oil but the filters catch the same amount of junk per mile.

 

In the early days of synthetic oils they did not have nearly the detergent capabilities as conventional oil. I got in the habit of running conventional every 3rd oil change and it would get dirty really fast so I'm certain the myth was true. I'm assuming that this is not longer true?

 

Thanks for the response Marc. I figured it was due to the warm climates.
Since I was changing my own now I was trying to see if there were any benifits to start going with 10W30 in the summer time. It's my daily driver if you couldn't tell by the mileage. Fall's coming so next time I think I'll try the Mobil1 or the Royal Purple as I'm not impressed by the castrol. I'd like to stick with a blend as I've run full synth in a different car and it sounded like crap compared to dino. No offense to the full synth guys.

 

Say DpezXK8, very impressive mileage on your vehicle. I hope my 2005 XKR does as well. In all those miles have you ever had a major engine or transmission issue? Also, at 170k how is your oil consumption?

 

It's Moble1 5w-30 every 5-7k, Got 114k,she uses literly no oil, runs smooth and quiet.

 

It's been a love hate relationship, Love to drive it-hate to fix it. Only major fix was the trans @ 150K but the fluid was never changed. Other than that pretty much standard issues. Just replaced the alternator, power steering pump went about 5k ago. Did front wheel bearings about 125K. Replaced front shock, bushings, ball joints about the same time. Did upper shock mounts recently but they actually looked pretty good still compared to others I've seen. Car still runs awesome and the no real notice in oil consumption. Sometimes I'll see a litlle puff of blue when I first start it but other than that I've never had to add any between changes.

 

10w-30 castrol synthetic every 5-7k miles She loves it and drives much better every time I change oil. :-) I put a lot of miles on the XJ super v8 so I change it every 4-5 months.

 

I use Penns Platinum 5-w30 every 5000 and as im probably the minority also use lucas synthetic with every change too. I havent had anyissues with oil consumption or major engine problems but I drive my car really hard atleast twice a week Im doin 135mph plus so that is more of a piece of mind with me and every time it ever goes to the shop they always tell me things look pretty clean and good.

 

I do oil twice a year and filter once a year milege never exceeds 12k in a year.

 

I use Valvoline MaxLife synth blend 10w-30 with Napa Gold (Wix) filter with the anti drain-back valve. Change every 3000 miles, about twice a year. My driving consists of mainly short trips, so I would be concerned about contaminants building up with a longer change interval. The engine is quiet at start up, doesn't leak or smoke, and consumption is minimal.

 

First oil change I have done since purchasing the car. Went with Castrol EDGE 10w30 with a K&N oil filter. We will see how it works. So far quite and smooooth.

 

I have had good luck with castrol gtx every 4500 and mobile one at 5k as long as it wasn't that extended life garbage (which I stupidly left in the motor for 7500 miles)

 

Mobile 1 10-30 every February 12 months ( I dont do more that 5000 miles a year).

 

I've only used Mobil 1 synthetic (5w 30) since getting the car at 68k miles. It's now got over 81k. I use a Wix filter but am thinking of trying out a Mann filter next time. They're more expensive but very well made and well reviewed.

I also do an oil analysis with each change via Blackstone labs (search for thread). Costs twenty bucks; thirty if you get a TBN test along with it (measures oil life). But once you get one TBN to establish how long your oil can last, it really isn't necessary after that.

With a filter swap at 5,000 miles and a slight top-up to compensate for loss from old filter, I will run the same oil up till 10k miles. The analyses I've had done show no reason to change it any sooner.

 

Not surprising you were not impressed with the Castrol "synthetic" as there was a big scandal about them a few years back. Turns out their supposed full synthetic was not full syn as advertised - it actually had some dino in it. There was a big court case (can't recall the name, exactly) but nothing really came out of it. I do not know if they ever changed their marketing to reflect what is in the product but be warned, there may be a reason it is cheaper than the rest.

There may be other good ones, but I would stick with Mobil 1 or Amsoil.

EDIT: Here is the story behind the Castrol bait & switch:

http://www.worldsbestoil.com/amsoil/...trol-court.htm

 

I have read that because of this US court ruling all the major US oil companies now use purified Group III as "synthetic". Only the boutique oil companies still use Group IV or V.

 

It was actually an arbitration decision, not a court case (I misspoke earlier) but yeah, the industry is following their guidelines. Tests still show that full, actual synthetic is better. Buyer beware.

 

i use Royal Purple and Motorcraft filters on all of my vehicles.

After some research, i found that the motorcraft filters are the same as the Pureolator One filters but they supposedly have a more expense longer lasting filter element in it then the off the shelf pureolator one filter.
and its a hell of allot less expensive.

 

I tried a couple types and found that Fram leaked, I now stick with Bosh and have used one Moble1 that was ok. have not tried any off brands, I don't need the hassel. Fram is made by Honeywell corp and uses paper and glues the ends of the cartrages. Bosh uses cloth and crimps end. My motor is worth thousand and two bucks more per change is well worth the cost.Oil doesn't wear out it gets contaminated and deluted with combustion materials, especally on short trips.(short story). My brother- in- law had a 90-91 Escort(Ford w/ 4 banger)had 220k on it when he sold it,still running. Plugs, what are plugs-air filter whats that. He changed oil and filter ABOUT 5 times.Like eveything else he had no maintenance.He left tools and everythig else out in the rain,rusted crap. Dumb ***. Lucky is better than smart.