synthetic...?

I have a 99' ext cab 4x4 sr5 3.4L with 285,000m on her. And she running strong. Change the oil about every 4,000m. Use 5w30 castrol oil. Should I go synthetic??? I got k&n cold air intake. 5speed, read some posts that people went synthetic at lower milage. Would appreciate some input

 

Absolutely! Particularly if you are where there are extremes of heat or cold.

There are (based on their chemistry) several different types of synthetics....and they are not all created equal. But, any one of them is far better than dinosaur oil.

 

I just switched to mobil 1 5w-30 full synthetic at 45k miles.

It gained me about 2mpg on the highway on my last trip Normally i'd be lucky to get 18mpg, and i was averaging 20.4


There are lots of people who say you can do make the switch at any mileage but 45k is the longest i've personally ever waited.

 

I switched mine years ago and have recently switched back.

It's like this: synthetic is a lot 'cleaner' and acts like a cleaner compared to carbon based conventional oil. I switched mine and ran about 5-6 changes when I noticed the oil pan developed a seeping leak around the aging OEM 1999 gasket. Asked a few guys that turn wrenches on the weekend dirt tracks and they all said this, 'the synthetic has cleaned the engine and slowly removed the built up carbon deposits. This is most likely the culprit behind the leak now. Swap back to conventional and it'll probably go away.' So I did swap back about 3 changes ago and the leak is now gone.

With that said, synthetic is good stuff. But be aware that the first 2-3 changes will scare you they'll be so dirty looking. After that, they'll almost look like the day you poured the oil in.

 

when its -30C here you wouldnt believe how a good sythetic oil makes for easier starts and faster warm ups. Ever since I switched I did notice leaking around the base pan also.

 

synthetic oil will reduce wear and add years to your engines life, that's why not a single engine made today uses regular oil anymore, except lawn mowers because they want those engines to wear out every 5 years so you buy a new one.

 

I'm not sure if I'd make the switch at 285K. You may develop leaks.

 

Wouldn't it be better to change the gasket and correctly repair the problem??? If there was "build-ups" of any sort, don't you worry that those same build-ups will create more problems in the future? To me, the fact that the synthetic was cleaning your motor is a good thing! Just my .02. Ed

 

+1 to all of this.

 

George Burns smoked cigars and drank hard liquor until the day he died at 113. What's a little carbon buildup gonna hurt? My FIL has an '82 with the 22r and it has rolled the odometer on conventional oil.

But yes, changing the pan gasket would be the proper thing to do. I have one waiting for the day to tear into it to do it. That day may be here soon.

 

I think you may be off on his age by a decade and some.

 

I wouldn't make the switch at that high of mileage. I had a high mileage 22r many years ago that i switched over to synthetic and caused all sorts of leaks. Also, at the mileage its not like you're going to get extra life out of it because you switched to synthetic.

 

There are some old wives tales that persist about synthetic oils. For example, in the early days they discovered that esters would make seals soften and swell, and PAO would make them dry and harden. The answer, was to formulate some combination of the two that splits the difference (and thankfully also results in a superb oil!). These issues were all solved a generation ago....yet they live on eternally here on the internet, where well meaning but ignorant folks rehash them over and over.....

 

With 285K....why change now. It's served you well.

 

Thats what i'm thinking

 

My first sig line down below.

You toss plastic oil in there and your 285K good luck could dissolve right in front of you.

Are you a big gambler? is the question. If so,,roll the dice.

 

Just acquired a 3.4 with 120k debating on going synthetic ..... which brand etc would you all recommend?

 

In Coachella, you are more interested in protection from very extreme summer heat, so any of these will do that job.

1st choice Redline. Ester based with some PAO for "balance". You will however not like the price.

2nd choice Amsoil. PAO based, but fortified with some ester. Again you won't like the price, and the company's distribution practices are ludicrous.

Distant 3rd choice Mobil 1. Group III based, so not as good as the two above (especially on very cold starts), but a passable oil at a descent price. (One note about Mobil 1: Back in the day it was PAO based, and this is where it earned its fine reputation. A few years ago, on the sly without saying a word (!), it switched to Group III. The result is a better price, but not as good an oil.)

In order to meet a reasonable price point, I would guess that most of the other regular branded oils out there these days are Group III, so most will be very similar to the present day Mobil 1.

 

I recommend Pennzoil Platnium. It's a true synthetic rather than cracked base oil.

Running synthetic in a high mileage engine can be risky if you have any sludge in there from past owners. The synthetic will clean up the engine, break off the sludge and deposits, and that debris could clog something up inside the engine. I've never seen it happen, but it's talked about a lot on the bob is the oil guy forums.

 

My experience was only 7 years ago so I'm thinking you might be wrong about it being fixed a decade ago. You just might be the ignorant one here.