Questions about Synthetic Oil

Hello all. My vehicle, as you all should know by now, is a 1996 Suburban, 5.7 liter vortec, 4X4, with 153,xxx miles on the clock. I plan on running this vehicle till the wheels fall off, and with that being said I am starting to consider changing to Mobil 1 synthetic oil. I have changed my oil religously every 3,000 with Valvoline Max Life, and AC-Delco oil filter as long as I have owned it anyway. I have a few questions though before I do anything.

1. Does this seem like a bad idea to any of you?

I really do love this vehicle and I hope to be driving it many years from now. I would like the extra protection, but I dont want to screw anything up in my high mileage engine. Any advise is much appreciated.

2. How should I go about making the switch?

Is it just as simple as draining the oil and filling it up with Mobil1 or is an engine flush required? I have heard it is better to not flush it, but to fill it with synthetic and change it sooner the first couple changes, then go to the normal changing interval, which leads me to my next question.

3. What change interval would you recommend, and what weight? Also what oil filter is best?

I know that you can go more miles on synthetic oil than on convetional before an oil change is required, but what is a good rule of thumb? What weight should I use? It says 5w-30 on the cap, and it gets cold here, so I'm assuming thats the way to go. Also I love my Delco stuff. Can I keep using my AC-Delco filter?

Thanks to all of you! I just need some help making this decision.

I switched my 03 Burb to synthetic at 100k (bought it used). I used the same weight and AC Delco filter. The first interval I changed at 3k but after that have changed the interval to 5k. You also have to keep in mind of your driving habits, I don't do a lot of towing or in towning driving but instead highway driving.

Treat the switch like a regular oil change. Drain, filter change, then refill. Don't forget to recycle.

Don't forget about your Trans and differential fluids as well.

good luck,

Sandman

In my 97 k1500 I switched to mobil 1 at around 90k and changed every 4-5,000 miles depending on my dirving. I did a compression test and leakage test on it at 140k and it passed everything like it was a brand new engine. My 03 had 40k on it when I bought it and a fresh oil change but at 43k I switched to mobil 1 and am going to change every 4,000 miles which is about every 6-7 months of a lot of short trips. I use cheap old fram filters and have for many miles on many vehicles with no problems what so ever. In my opinion, synthetic oil is the way to go and it is the only thing I will use in my vehicles.

Like Sandman said, don't overlook the tranny and gears and your truck should go along time. I plan on flushing the tranny at 50k and will probably use synthetic and not worry about it again till around 100k or so.

I use synthetic oil in my vehicles,and generally use a 10,000 to 12,000 mile change interval. Roughly halfway through this period I will change just the filter and top off the oil to compensate what is lost through changing the filter. I use Mobil 1 . I also use A C Delco filters, and would recommend staying with them as they are a great filter. Here is a link to a study on oil filters, and A C Delcos came out with excellent results,(Fram didn't fare so well as their quality has really declined over the years,):http://minimopar.knizefamily.net/oilfilterstudy.html
You can change the oil sooner the first time you switch to synthetic as the synthetic tends to have a "detergent" effect on your engine cleaning up deposits and sludge, which your oil filter will capture, so changing that sooner the first time will help your engine.

Wow, great replies. Thanks! I drained it out tonight, slapped a new AC-Delco filter on it, and filled it with Mobil1 5w-30 full synthetic. I plan to change it at about 3,000 miles the first change, and then around 6,000 after that. Those seem like safe numbers to me.

As far as the transmission and differential goes, what kind of synthetic would you use? (Mobil1, Royal Purple, or others?) I'm sure the differential would benifit from a fluid change to synthetic, I probably wouldn't have to worry about it for a while after that. I have only about 1,000 miles on my tranny rebuild. Would you take it in to get flushed and then refill with synthetic? or would a drain/filter and refill with synthetic be sufficient? Thanks to all the replies it helps me out alot! Keep em coming!

I run Castrol Syntec 5W-30 in my 400.000 mile (original owner) Suburban. Change at 7-8,000 miles and put on a K&N HP3002 filter.

I have found Redline D4 to be the best synthetic ATF, about $10/quart; change at 30,000 mile intervals. Be sure to install a good-sized external trans cooler, the factory "HD" pipe in the radiator is almost useless.

Torco synthetic 85-140 for the rear end at 100,000 mile intervals. Be sure to put in the GM additive if you have Posi.