Newly acquired 04, needs first oil change, but?

Here's the deal. It's time for my new to me 04 to get her oil changed. Currently sitting on 218K miles. I know you can go from conventional to synthetic but not supposed to go from synthetic to conventional. I'm no mechanic by any means so forgive me if some of these are dumb questions.

So my question is how do I know what is currently in there? (from what I have read you can't tell without getting it tested) I was planing on using Valvoline High Milage (the red carton). I've used that in past vehicles. But if it currently has synthetic in it that might not be a good idea.

Is the milage to high to just switch to something like Mobile 1 High Milage? Or something like the synthetic high milage blend?

Part of me thinks I'm overthinking it and just grab a good blend and go with it. Your input would be greatly appreciated. Thank you.

Everything i have read says it`s perfectly fine to switch back and forth. Some people say that you shouldn`t switch to synthetic on high mileage vehicles if it has a poor maintenance record but if it was treated well i wouldn`t hesitate to switch.

i think the issue is switching to between high mileage and regular oils actually because of the additives for the seals and gaskets in the High mileage mixes.

I never understood how switching back-and-forth can cause problems other than leaking when switching from conventional to synthetic. Even then, the problem isn't the oil. It's just that the syn is able to leak out the worn seals that the conventional couldn't. The problem isn't the oil, it's the worn seals. The synthetic oil is still the better oil for it's protection and longevity qualities.

If it were me, I'd base my decision on what I plan to run every time so I'm not researching it every X thousand miles. I'd also probably run a blend this time around since I don't know what's currently in it and it'd be like a transitional period to where I could run whichever from then on- full conventional or full synthetic. I really don't see how or why it would matter, but "gradually" switching one way or the other would just make me feel better.

If running syn-blend or full-syn leads to more leakage, then switch back to conventional and just change it more frequently since it doesn't last as long as synthetic.

Thanks for the info guys it's appreciated. I just went wit the valvoline high milage blend. She really only gets driven on the weekends and on family trips. Not to say I want something bad to happen but I'm not running up the miles.

Just a side note. It's pretty sad I can buy some ramps from walmart, oil, and filter and only spend slightly more than if I took it to a shop. Granite it cost me time, but only a few minutes. Not to mention next time will be even cheaper because I'll have the ramps already.

Thanks again.

cntryislandboy said:

Thanks for the info guys it's appreciated. I just went wit the valvoline high milage blend. She really only gets driven on the weekends and on family trips. Not to say I want something bad to happen but I'm not running up the miles.

Just a side note. It's pretty sad I can buy some ramps from walmart, oil, and filter and only spend slightly more than if I took it to a shop. Granite it cost me time, but only a few minutes. Not to mention next time will be even cheaper because I'll have the ramps already.

Thanks again.

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And the shops use crap oil.

Rocket Man said:

And the shops use crap oil.

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And crap filters
And they rush through it (I let mine drain for at least an hour while I clean and rotate my wheels)
And they usually under- or over-tighten the drain plug and filter

iamdub said:

And crap filters
And they rush through it (I let mine drain for at least an hour while I clean and rotate my wheels)
And they usually under- or over-tighten the drain plug and filter

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While this is the first time I've changed my Tahoe oil, I used to change my jeep all the time. And I'd also let my oil drain for an hour or 2 while I worked on other chores around the house. It's actually relaxing and almost therapeutic in a pay.

thats a lot of miles. Did the previous owner provide any records of maintenance & preventative maint? You need to refresh every single fluid & filter in that rig. If you have the owners manual it should have just about everything listed somewhere towards the back. I have PDF from the w/s manual if you want to use that as a guide.

cntryislandboy said:

It's actually relaxing and almost therapeutic in a pay.

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Yes. You get a stronger sense of accomplishment, you know it was done to YOUR liking and it strengthens the bond between you and your machine. It's new to you so you should be the one checking it over inside and out, topside and bottom.