Complete tune up

Hiya,
I have an 01 4runner with 155,000 miles. After last oil change, she started to idle different and I smelled burning oil. Anywho, looked underneath and sure enough, oil everywhere. After the oil change, they mentioned that I may see some oil due to some spillage from removing oil filter. So, didn't think much of it. After looking over the receipt today, I noticed that they used Ow20 instead of the 5w30, they normal do. Not sure if this is significant but thought I would mention it and see if there would be any negativity, doing so? I also noticed on the receipt, under service comments, it says minor engine oil leak and transmission/transaxle fluid leak. This wasn't mentioned to me, so therefore, i didnt even look. I will go forward, studying my receipts. But, in the down time of covid, I have learned to do some of my own maintenance on an old ford motorhome I decided to get road ready and sell. Im now going to tackle the 4runner. With that said, I'm going to go ahead and do a full tune up, draining all fluids..oil, transmission, differential, etc..plugs/wires, all belts, water pump and hoses. My main question would be, should I replace everything with full synthetic at this point? With a product such as amsoil? I will be her last owner so we are in it for the long haul.

 

First off, replace that oil with 5-30. I have a 96 4runner with 475,000 and have never used synthetic. I heard that seals could start leaking when installing on an older vehicle. The most important thing is to replace oil/filter every 3000-5000 miles.

 

i have a '97 4runner...with 254k..and have used synthetic for many many miles, with little or no issues

 

So the Synthetic in older cars like 1980's or older can indeed leak...because tolerances in the engines sucked back then.

Modern cars 2000 or newer? Much different story. Way better tolerances and seals.

Also, if you watch over the years, manufacturers have been lowering the weight of the recommended oil on the same exact engines. Pretty sure the 2014 Sienna we had that (that was totaled) and the 2017 Sienna replacement had different recommended oil. Same engine.

0W20 should be ok. I would still run the recommended oil going forward. The difference between 0W20 vs 5w30 is small enough to ignore until the next change interval.