switch to Fully Synthetic?

when I bought my truck it had 128,000mi and I didnt know what oil the previous owner used, so I threw Castrol GTX High Mileage in her and have been using since with K&n oil filter. I have heard nothing but good things about Mobil 1 Full Synthetic and I want to try it, but the saying goes just go with what youve been using. Is this change worth it? or not? I currently have 140k. The reason being I really want to make the switch is from when I put Mobil 1 in my gear case and the difference it made was remarkable.

 

Personally, I would change to full synthetic if you are planning on putting on a bunch of miles. It will run cleaner overall and clean out any crud left over from dino oil. The downside to this is that if any of that crud is keeping old gaskets from leaking, then you could start to develop leaks. If the vehicle has been well maintained, this may not be a problem. This comes from my own experiences from using synthetic oil. It's all I use now.

 

hey thank you for the advice, i think im gonna try it!

 

No problem. I hope it goes well for you. IMO, it's good for the long run if you plan putting some miles on it. Better protection, fewer oil changes, possibly better mpg. Other people might have different opinions and these are just based on my experiences.

 

It's not necessary to do that.

Synthetics do clean better but it's not gonna disolve everything in a matter of 1000 miles. I've never flushed anything and never noticed any difference in the first oil change using synthetics to last oil changes.

 

ok good to know. and how often should I change my oil with fully synthetic? should it be more ofter due to the high mileage of my truck?

 

I change mine every 5K with a filter....works fine.

 

In terms of synthetics & when to change them, is a heated debate really.

There's the theory that synthetics can stay in your engine longer because they don't break down. Technically, that's true - however - there are other factors involved that play into the equation whether or not you should leave it in longer than recommended intervals. Lots of guys here get their oil analyzed..... and that'll tell you whether or not the oil can be run for longer intervals.

For me personally, I've never had an oil analysis. I change mine (oil & filter) every 5K miles (as recommended by my owners manual) using Mobile 1. At that point, the oil is really dark/dirty and it's just *peace of mind*. I don't mind paying the extra money on the synthetics.

For your engine with that many miles, it might be a good idea to change it regularly.

 

im using amsoil extended life,every 20,000 miles or once a year.buddy did oil test with amsoil with 54000 miles on it.then took brand new quart of penzoil (regular oil) from walmart to get sampled.amsoil with 54000 beat brand new penzoil in the tests.go figure.oh yeah that used oil came out of a s10 blazer 4.3 motor.good luck.

 

thanks for all the great info guys, very much appreciated

 

Actual Results?? I'm interested to see how much worse that new oil faired than used oil...

 

brunes ill see if i can get that info.not to sure though,been 3yrs ago.later

 

Since you already get good results with Castrol GTX, why not move up to Castrol Syntec? It's marketed as a "fully synthetic" oil but is really a group 3 oil. I run it myself. The price is right. It flows like a synthetic, but seems not to leak as much as Mobil 1 in high mileage engines. In this respect, it behaves like a conventional oil, which is a good thing for the narrow purpose of non-leakage.

Don't get me wrong. Mobil 1 is an excellent product. Amsoil is great. Royal Purple is great.

Syntec runs a little cheaper, does almost the same thing, and it won't leak quite as easily. This might lend some peace of might to someone pondering the switchover to synthetic.

 

Honestly because Ive just heard more great things about Mobil 1. but since you have mentioned it Im gonna look into it. thanks for the advice, Ill let you know what I end up going with and then the results.

 

Re frequency of oil changes:
Synthetic doesn't extend your oil change dates.
Synthetic is manufactured using regular oil, and additives.
Needs higher temperatures to break down.
Has better cold-start viscosity.

Many folks say their engine never burns oil. All engines burn oil. The level on the dipstick might never change, but it's due to carbon, and by-products of combustion going into the oil. This is why it looks dirty, and why you change it. Synthetic oil doesn't change this, you still get dirty oil at the same rate.

So the debate is ... should one use synthetic @ the regular intervals, or use the extra $ to change with non-synth more often.
Heavy-use vehicles in hot climates ... synth would be better. Cold climates ... synth would be better at startup.

If you can afford it - synth is better, so long as the oil change intervals are adhered to. Me ... I change mine more often ... every 5000km, instead of 8000, and use non-synth.

 

"So why'd you hit me?" "Cuz you were thinking with yer dipstick.... Jimmy."

Sorry totally pointless but I couldn't resist.

 

Carquest fully synthetic 5w-20 with their premium filter. Change my oil every 5,000 miles. No problems yet @ 48,5xx miles. 6 qts. and filter is only $35

 

synthetic all the way.. royal purple in the engine gear lube and differenials..

 

If you really want to learn about oils check bitog.com. The new craze over there is PP since it has been getting excellent UOAs...